IBM SC34-7012-01 Bedienungsanleitung

CICS Transaction Server fo r z/OSVersi on 4 R elease 1Recovery and Restart GuideSC34-7012-01

viii CICS TS for z/OS 4.1: Recovery and Restart Guide

Recovery from failures associated with the coupling facilityThis topic deals with recovery from failures arising from the use of the couplingfacility,

CICS recovers after a cache failure automatically. There is no need for manualintervention (other than the prerequisite action of resolving the underl

region that was not sharing the data set at the time the lost locks conditionoccurred, and on RLS access requests issued by any new units of work in C

simultaneously all data sets in use when the lock structure fails, each data set canbe restored to service individually as soon as all its sharing CIC

Recovery from the failure of a sysplex is just the equivalent of multiple MVSfailure recoveries.Transaction abend processingIf, during transaction abe

The exit code then executes as an extension of the abending task, and runs at thesame level as the program that issued the HANDLE ABEND command thatac

1. CICS invokes DFHREST only when RESTART(YES) is specified in atransaction’s resource definition.2. Ensure that resources used by restartable transac

v CICS remains operational, but the task currently in control terminates.v CICS terminates (see “Shutdown requested by the operating system” on page29

96 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 9. Communication error processingThe types of communication error that can occur include terminal error processingand intersystem communicatio

Changes in CICS Transaction Server for z/OS, Version 4Release 1For information about changes that have been made in this release, please refer toWhat&

The TEP is entered once for each terminal error, and therefore should be designedto process only one error for each invocation.Intersystem communicati

Part 3. Implementing recovery and restartThis part describes the way you implement recovery and restart for CICS regions.© Copyright IBM Corp. 1982, 2

100 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 10. Planning aspects of recoveryWhen you are planning aspects of recovery, you must consider your applications,system definitions, internal do

Question 5: If a data set becomes unusable, should all applications be terminated whilerecovery is performed? If degraded service to any application m

Before any design or programming work begins, all interested parties should agreeon the statement—including:v Those responsible for business managemen

v If a user’s printer becomes unusable (because of hardware or communicationproblems), consider the use of alternatives, such as the computer center’s

and general log data to log streams defined to the MVS system logger. Formore information, see Chapter 11, “Defining system and general logstreams,” o

normal conditions. They should, nevertheless, be tested as far as possible, to ensurethat they handle the functions for which they are designed.CICS f

Chapter 11. Defining system and general log streamsAll CICS system logging and journaling is controlled by the CICS log manager,which uses MVS system

x CICS TS for z/OS 4.1: Recovery and Restart Guide

System log streamsThese are used by the CICS log manager and the CICS recovery managerexclusively for unit of work recovery purposes. Each system log

CICS log manager connects to its log stream automatically during systeminitialization, unless it is defined as TYPE(DUMMY) in a CICS JOURNALMODELresou

Model log streams for CICS system logsIf CICS fails to connect to its system log streams because they have not beendefined, CICS attempts to have them

However, using model log streams defined with the CICS default name are alwaysassigned to the same structure within an MVS image. This may not give yo

Varying the model log stream name:To balance log streams across log structures, using model log streams meanscustomizing the model log stream names. Y

work. With this information, CICS continues reading backwards, but this timereading only the records for units of work that are identified in the acti

v If a system log stream exceeds the primary storage space allocated, it spills ontosecondary storage. (For a definition of primary and secondary stor

Writing user-recovery dataAbout this taskYou should write only recovery-related records to the system log stream. You cando this using the commands pr

About this taskThe dddd value specifies the minimum number of days for which data is to beretained on the log.You are strongly recommended not to use

2. Define a general log stream for forward recovery data. If you do not define ageneral log stream, CICS attempts to create a log stream dynamically.

Part 1. CICS recovery and restart conceptsIt is very important that a transaction processing system such as CICS can restartand recover following a fa

Merging data on shared general log streamsUnlike system log streams, which are unique to one CICS region, general logstreams can be shared between man

About this taskThe CICS-supplied group, DFHLGMOD, includes a JOURNALMODEL for the logof logs, called DFHLGLOG, which has a log stream name of&USER

v In a format compatible with utility programs written for versions of CICS thatuse the log manager for logging and journaling.See the CICS Operations

Operating a recovery process that is independent of time-stamps in the system logdata ensures that CICS can restart successfully after an abnormal ter

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Chapter 12. Defining recoverability for CICS-managedresourcesThis section describes what to do to ensure that you can recover the resourcescontrolled

SPURGE({NO|YES})This option indicates whether the transaction is initially system-purgeable; thatis, whether CICS can purge the transaction as a resul

Recovery for filesA CICS file is a logical view of a physical data set, defined to CICS in a fileresource definition with an 8-character file name.A C

Forward recoveryFor VSAM files, you can use a forward recovery utility, such as CICSVR, whenonline backout processing has failed as a result of some p

uses the ICF catalog entry recovery attributes instead of the FILE resource. Toforce CICS to use the FILE resource attributes instead of the catalog,

2 CICS TS for z/OS 4.1: Recovery and Restart Guide

VSAM files accessed in RLS modeIf you specify file definitions that open a data set in RLS mode, specify therecovery options in the ICF catalog.The re

INQUIRE DSNAME command returns values from the VSAM base cluster block(BCB). However, because base cluster block (BCB) recovery values are not set unt

About this taskIf you use XFCNREC to suppress open failures that are a result of inconsistenciesin the backout settings, CICS issues a message to warn

- File is defined with RECOVERY(ALL): the open fails.– Base cluster has RECOVERY(ALL):- File is defined with RECOVERY(NONE): the open fails.- File is

For more information about allocation and space requirements, see the CICS SystemDefinition Guide.) For extrapartition transient data considerations,

Making intrapartition TD physically recoverable can be useful in the case of someCICS queues. For example, after a CICS failure, you might choose to r

Recovery for extrapartition transient dataCICS does not recover extrapartition data sets. If you depend on extrapartitiondata, you will need to develo

Output extrapartition data setsThe recovery of output extrapartition data sets is somewhat different from therecovery of input data sets.For a tape ou

Define temporary storage queues as recoverable using temporary storage modelresource definitions as shown in the following example define statements:C

About this taskCICS uses Business Transaction Services (BTS) to ensure that persistent messagesare recovered in the event of a CICS system failure. Fo

Chapter 1. Recovery and restart facilitiesProblems that occur in a data processing system could be failures withcommunication protocols, data sets, pr

2. For each local request queue, define a QLOCAL object. Use the followingcommand:DEFINEQLOCAL('queuename')DESCR('description')PRO

not usable, message DFHPI0117 is issued, and CICS continues without BTS, usingthe existing channel-based container mechanism.If a CICS failure occurs

140 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 13. Programming for recoveryWhen you are designing your application programs, you can include recoveryfacilities that are provided by CICS; fo

v Progress transaction, to check on progress through the application. Such afunction could be used after a transaction failure or after an emergencyre

SAA-compatible applicationsThe resource recovery element of the Systems Application Architecture®(SAA)common programming interface (CPI) provides an a

committed in one unit of work, but the transaction is to continue with one ormore units of work for further processing.3. Where file or database updat

back out only the updates made during that individual step; the application isresponsible for restarting at the appropriate point in the conversation,

v Data tables (user-maintained)v Coupling facility data tablesCICS can return all these resources to their status at the beginning of an in-flightunit

Procedurev Arrange for all transactions to access files in a sequence agreed in advance. Thiscould be a suitable subject for installation standards. B

In general, forward recovery is applicable to data set failures, or failures insimilar data resources, which cause data to become unusable because it

The abend processing should analyze the cause of failure as far as possible, andrestart the task if appropriate. Ensure that either the user or the ma

About this taskSuch queuing can be done on a transient data queue associated with a terminal. Aspecial transaction, triggered when the terminal is ava

For example, if file input and output errors occur (where the default action ismerely to abend the task), you might want to inform the master terminal

v DTB takes place only after program level abend exits (if any) have attemptedcleanup or logical recovery.Transaction restart after DTBFor each transa

v Send a message to the terminal operator if, for example, you believe that theabend is due to bad input data.Information that is available to a progr

START TRANSID commandsIn a transaction that uses the START TRANSID command to start other transactions,you must maintain logical data integrity.You ca

About this taskThere are two forms of locking:1. The implicit locking functions performed by CICS (or the access method)whenever your transactions iss

Recoverable filesFor VSAM or BDAM files designated as recoverable, the duration of the lockingaction is extended. For VSAM files, the extended locking

The extended period of locking is needed to avoid an update committed by onetask being backed out by another. (Consider what could happen if thenonext

The backout fails because a duplicate key is detected in the AIX indicated bymessage DFHFC4701, with a failure code of X'F0'. There is no lo

Another way is to shut down CICS with an immediate shutdown and perform theforward recovery, after which a CICS emergency restart performs the backwar

enqueuing on temporary storage queues where concurrently executing tasks canread and change queue(s) with the same temporary storage identifier. (See“

After a task has issued an ENQ RESOURCE(data-area) command, any other taskthat issues an ENQ RESOURCE command with the same data-area parameter issusp

v If both deadlocked resources are CICS resources (but not both VSAM resources),or one is CICS and the other DL/I, CICS abends the task whose DTIMOUTp

Procedurev Enable them in PLT programs in the first part of PLT processing.v Specify them on the system initialization parameter, TBEXITS. This takes

XFCLDEL global user exitXFCLDEL is invoked when backing out a unit of work that performed a writeoperation to a VSAM ESDS, or a BDAM data set.XFCBOVER

Chapter 14. Using a program error program (PEP)The program error program (PEP) gains control after all program-level ABEND exitcode has executed and a

7. The CICS transaction failure program, DFHTFP, links to DFHPEP beforetransaction backout is performed. This means resources used by the abendingtran

When you have corrected the error, you can re-enable the relevant installedtransaction definition to allow terminals to use it. You can also disable t

166 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 15. Resolving retained locks on recoverableresourcesThis section describes how you can locate and resolve retained locks that arepreventing ac

v In the event of an emergency restart, when CICS backs out all those transactionsthat were in-flight at the time of the CICS failure (emergency resta

The RLS quiesce and unquiesce functionsThe RLS quiesce and unquiesce functions are initiated by a CICS command in oneregion, and propagated by the VSA

Note:1. A suitably-authorized user application program (AOR1 in the diagram) issuesan EXEC CICS SET DSNAME(...) QUIESCED command (or a terminal operat

(4a) SMSVSAM uses the coupling facility to propagate the request to the otherSMSVSAM servers in the sysplex.5. The CICS RLS quiesce exit program sched

With the new RLS quiesce mechanism, you do not have to close a data setto take a non-BWO backup. However, because this causes new transactionsto be ab

Lost locks recovery completeA quiesce interface function initiated by VSAM. VSAM takes actionassociated with a sphere having completed lost locks reco

Note: If your file definitions specify an LSR pool id that is built dynamically byCICS, consider using the RLSTOLSR system initialization parameter.v

The remainder of this topic on switching to non-RLS access mode describes theoptions that are available if you need to switch to non-RLS mode and arep

About this taskHowever, it does know about the uncommitted changes that are protected by suchlocks, and why the changes have not yet been committed su

v Commit failure, where a unit of work has failed during the commit action. Thecommit action may be either to commit the changes made by a completed u

4. If a unit of work has been shunted with a different CAUSE and REASON,review the descriptions of these values in the INQUIRE UOWDSNFAIL command tode

The recovery manager also drives:v The backout processing for any units of work that were in a backout-failed stateat the time of the CICS failurev Th

Diagnostic messages DFHFC3003 and DFHFC3010 are issued for each log record.If a data set has both indoubt-failed and other (backout- or commit-) faile

CEMT INQUIRE UOWDSNFAIL DSN(’RLS.ACCOUNTS.ESDS.DBASE1’)STATUS: RESULTSDsn(RLS.ACCOUNTS.ESDS.DBASE1 ) Dat DelUow(AA6DB080C40CEE01) RlsDsn(RLS.ACCOUNTS.

X’AA6DB08AC66B4000’ and file ACCNT1 .Update was a write-add made by transaction WKLY at terminal T583under task number 00027. Key length 4, data lengt

v Do not use DENYNONRLSUPDATE if you run non-RLS work after specifyingPERMITNONRLSUPDATE. The permit status is automatically reset by the CICSregions

Coupling facility data table retained locksRecoverable coupling facility data table records can be the subject of retained locks,like any other recove

Chapter 16. Moving recoverable data sets that have retainedlocksThere may be times when you need to re-define a VSAM data set by creating anew data se

The following access method services examples assume that CICS.DATASET.A needsto be redefined and the data moved to a data set named CICS.DATASET.B, w

This makes the data set unavailable while the move from old to new is inprogress, and also allows the following unbind operation to succeed.4. Issue t

v Create a new empty data set into which the copy is to be restored, and useIMPORT to copy the data from the exported version of the data set to the n

Chapter 17. Forward recovery proceduresIf a data set that is being used by CICS fails, perhaps because of physical damageto a disk, you can recover th

Forward recovery journal names are of the form DFHJnn where nn is anumber in the range 1–99 and is obtained from the forward recovery log id(FWDRECOVL

Recovery of data set with volume still availableThe procedure described here is necessary to preserve any retained locks that areheld by SMSVSAM again

9. Alter the new data set nameUse access method services to rename the new data set to the name of the olddata set.ALTER CICS.DATASETB NEWNAME(CICS.DA

There are several methods you can use to recover data sets after the loss of avolume. Whichever method you use (whether a volume restore, a logical da

This is because CICS cannot run the lost locks recovery process until the data setsare available, and the data sets are made available only after the

This clears the SMSVSAM CFVOL-QUIESCED state and allows SMSVSAMRLS access to the volume. CICS ensures that access is not allowed to thedata sets that

PIDS/565501800 LVLS/510 MS/DFHFC0152 RIDS/DFHFCCA PTFS/UN92873REGS/GR15 VALU/00000008 PCSS/IDARETLK PRCS/000000A9+DFHFC0312 ADSWA03A Message DFHFC0152

effect in CICS region ADSWA03C was shown by the following response to anINQUIRE UOWDSNFAIL command for data setRLSADSW.VF01D.BANKACCT:INQUIRE UOWDSNFA

work. Assuming that all CICS regions are active, and there are no indoubtUOWs, lost locks processing, for all data sets except the ones on the failedv

waits for indoubt resolution before allowing general access to the data set. In sucha situation you can still release the locks immediately, using the

ROUTE *ALL,VARY SMS,SMSVSAM,TERMINATESERVER8. When all SMSVSAM servers were down, we deleted the IGWLOCK00 lockstructure with the MVS command:VARY SMS

2. If the failure occurs during the execution of a CICS syncpoint, where theconversation is with another resource manager (perhaps in another CICSregi

that before running SHCDS CFREPAIR, the restored user catalog must be importconnected to the master catalog on all systems (see the “Recovering Shared

In these cases, you can resolve the cause of the failure and try the whole processagain.This topic describes what to do when the failure in forward re

1) Force shunted indoubt units of work using SET DSNAME(...)UOWACTION(COMMIT | BACKOUT | FORCE).Before issuing the next command, wait until the SET DS

Procedure for failed non-RLS mode forward recovery operationIf you are not successful in applying all the forward recovery log data to a restoredbacku

202 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 18. Backup-while-open (BWO)The BWO facility, together with other system facilities and products, allows you totake a backup copy of a VSAM dat

forward-recovery logs. Long-running transactions, automated teller machines, andcontinuously available applications require the database to be up and

Hardware requirementsThe concurrent copy function is supported by the IBM®3990 Model 3 with theextended platform and the IBM 3990 Model 6 control unit

How you request BWOYou can define files as eligible for BWO in one of two ways.ProcedureDecide which method you want to use for data sets:v If your da

v But if you specify BWO(TYPECICS), and the PTF has not been applied, and youhave not specified LOG(ALL) and a forward recovery log stream name, BWOpr

When the operator replies to IXC402D, the CICS interregion communicationprogram, DFHIRP, is notified and the suspended tasks are abended, and MROconne

Removing BWO attributesIf you want to remove BWO attributes from your data sets, you must follow thecorrect procedure to avoid problems when taking su

After an uncontrolled or immediate shutdown, further BWO backups might betaken by DFSMShsm, because the BWO status in the ICF catalog is not reset. Th

Each of these operations is discussed in the following sections.File openingDifferent processing is done for each of the three cases when a file is op

v If the file was defined with BACKUPTYPE(STATIC) and the ICF catalogindicates that the data set is already ineligible for BWO, CICS sets theBACKUPTYP

v If the file was defined with BACKUPTYPE(STATIC) and the ICF catalogindicates that the data set is already ineligible for BWO, the ICF catalog is not

Shutdown and restartThe way CICS closes files is determined by whether the shutdown is controlled,immediate, or uncontrolled.Controlled shutdownDuring

When you use DFSMShsm, you still use DFSMSdss as the data mover. You canspecify this using the DFSMShsm SETSYS command:SETSYS DATAMOVER(DSS)The DFSMS

DFSMSdfp must now disallow the pending change to ‘BWO enabled’ (andDFSMSdss must fail the backup) because, if the split did not finish before theend o

each CICS allows all units of work with updates for the data set to complete, andthen they write the tie-up records to the forward recovery log and th

The forward recovery utility should ALLOCATE, with DISP=OLD, the data set thatis to be recovered. This prevents other jobs accessing a back level data

The CICS recovery manager then uses the information retrieved from the systemlog to:v Back out recoverable resources.v Recover changes to terminal res

An assembler program that calls DFSMS callable services*ASM XOPTS(CICS,NOEPILOG,SP)** A program that can be run as a CICS transaction to Read and Set*

DS 30CDATEVAL DS 8C Date value from BWO recovery pointSUCMSG1 DS 8C Message textTIMEVAL DS 8C Time value from BWO recovery pointSUCMSG2 DS C Message t

MVC BWOFLAGS(12),ZEROESLA R4,1(0)CLI BWOC1,C’0’BE PRGBIT2ST R4,BWOF1 Set BWO indicator 1 if requiredPRGBIT2 DS 0HCLI BWOC2,C’0’BE PRGBIT3ST R4,BWOF2 S

MVC SUCMSG1(8),SUCTXT1MVC SUCMSG2(1),SUCTXT2UNPK KEYWORK(9),BWOTIME(5) Make date printableTR KEYWORK(8),HEXTAB-C’0’MVC DATEVAL(8),KEYWORKUNPK KEYWORK(

222 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 19. Disaster recoveryIf your CICS system is normally available about 99 percent of the time, it would bewise to look at your disaster recovery

acceptable. If you are located in an area prone to hurricanes or earthquakes, forexample, a disaster recovery site next door would be pointless.When y

v How critical and sensitive your business processes are: the more critical they are,the more frequently testing may be required.Six tiers of solution

Your disaster recovery plan has to include information to guide the staffresponsible for recovering your system, from hardware requirements to day-to-

Tier 1Tier 1 provides a very basic level of disaster recovery. You will lose data in thedisaster, perhaps a considerable amount. However, tier 1 allow

12 CICS TS for z/OS 4.1: Recovery and Restart Guide

The advantage of tier 3 is that you should be able to provide a service to yourusers quite rapidly. You must assess whether the loss of data will prev

The advantage of these methods is their low cost.The disadvantages of these methods are:v Recovery is slow, and it can take days or weeks to recover.v

Tier 4 closes the gap between the point-in-time backups and current onlineprocessing recovery. Under a tier 4 recovery plan, site one acts as a backup

v Cost is higher than for the tier 1 to 3 solutions, because you need dedicatedhardware, software, and communication links.Tier 5 - two-site, two-phas

Figure 24 summarizes the tier 6 solution.Tier 6, minimal to zero data loss, is the ultimate level of disaster recovery.There are two tier 6 solutions,

support the XRC DFSMS/MVS host, and one for the recovery 3990, this allows atotal of 86 km (53.4 miles) between the 3990s. If you use channel extender

Disaster recovery and high availabilityThis topic describes the tier 6 solutions for high availability and data currencywhen recovering from a disaste

v IMS write-ahead data set (WADS) and IMS online log data set (OLDS)v ACBLIB for IMSv Boot-strap data set (BSDS), the catalog and the directory for DB

where there is a high volume of transactions, but each transaction is typically lessthan 200 dollars in value.Other benefits of PPRC and XRCPPRC or XR

between the primary and secondary sites is interrupted. Remote logging is only aseffective as the currency of the data that is sent off-site. RRDF tra

Chapter 2. Resource recovery in CICSBefore you begin to plan and implement resource recovery in CICS, you shouldunderstand the concepts involved, incl

You should ensure that a senior manager is designated as the disaster recoverymanager. The recovery manager must make the final decision whether to sw

CICS VSAM Recovery QSAM copyCICS VSAM Recovery (CICS VR) provides a QSAM copy function that can copyMVS log streams to a QSAM data set.Copies of the Q

If a disaster occurs at the primary site, your disaster recovery procedures shouldinclude recovery of VSAM data sets at the designated remote recovery

Part 4. Appendixes© Copyright IBM Corp. 1982, 2010 241

242 CICS TS for z/OS 4.1: Recovery and Restart Guide

NoticesThis information was developed for products and services offered in the U.S.A.IBM may not offer the products, services, or features discussed i

Such information may be available, subject to appropriate terms and conditions,including in some cases, payment of a fee.The licensed program describe

BibliographyCICS books for CICS Transaction Server for z/OSGeneralCICS Transaction Server for z/OS Program Directory, GI13-0536CICS Transaction Server

CICS Shared Data Tables Guide, SC34-7017CICSPlex SM books for CICS Transaction Server for z/OSGeneralCICSPlex SM Concepts and Planning, SC34-7044CICSP

AccessibilityAccessibility features help a user who has a physical disability, such as restrictedmobility or limited vision, to use software products

v Working storagev Any LU6.2 sessionsv Any LU6.1 linksv Any MRO linksThe resources CICS retains include:v Locks on recoverable data. If the unit of wo

248 CICS TS for z/OS 4.1: Recovery and Restart Guide

IndexAabend handling 95, 151ACID properties, of a transaction 20activity keypointsdescription 22ADCD abend 159AFCF abend 159AFCW abend 159AIRDELAY 39A

DL/I (continued)implicit enqueuing upon 158intertransaction communication 146schedulingprogram isolation scheduling 158documenting recovery and restar

locking (continued)implicit locking on recoverablefiles 156in application programs 154locks 14log of logsfailures 119logical levels, application progr

system log streambasic definition 104system logslog-tail deletion 114system or abend exit creation 95system recovery table (SRT)definition of 104user

Readers’ Comments — We'd Like to Hear from YouCICS Transaction Server for z/OSVersion 4 Release 1Recovery and Restart GuidePublication No. SC34-7

Readers’ Comments — We'd Like to Hear from YouSC34-7012-01SC34-7012-01Cut or FoldAlong LineCut or FoldAlong LineFold and Tape Please do not s

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When a lock is first acquired, it is an active lock. It remains an active lock untilsuccessful completion of the unit of work, when it is released, or

– EXEC CICS CREATE CONNECTION COMPLETE– EXEC CICS DISCARD CONNECTION– EXEC CICS DISCARD TERMINALA UOW that does not change a recoverable resource has

CICS recovery managerThe recovery manager ensures the integrity and consistency of resources (such asfiles and databases) both within a single CICS re

CICS Transaction Server fo r z/OSVersi on 4 R elease 1Recovery and Restart GuideSC34-7012-01

v Managing the state, and controlling the execution, of each UOWv Coordinating UOW-related changes during syncpoint processing for recoverableresource

v Notification that the resource is not available, requiring temporary suspension(shunting) of the UOWv Notification that the resource is available, e

others. This can happen, for example, if two data sets are updated and the UOWhas to be backed out, and the following happens:v One resource backs out

Resynchronization after system or connection failureUnits of work that fail while in an indoubt state remain shunted until the indoubtstate can be res

CICS also writes “backout-failed” records to the system log if a failure occurs inbackout processing of a VSAM data set during dynamic backout or emer

v User journaling is entirely under your application programs’ control. You writerecords for your own purpose using EXEC CICS WRITE JOURNALNAMEcommand

24 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 3. Shutdown and restart recoveryCICS can shut down normally or abnormally and this affects the way that CICSrestarts after it shuts down.CICS

v The DFHCESD program started by the CICS-supplied transaction, CESD,attempts to purge and back out long-running tasks using increasingly strongermeth

this indicator to determine the type of startup it is to perform. See “How thestate of the CICS region is reconstructed” on page 34.v CICS writes warm

NoteBefore using this information and the product it supports, read the information in “Notices” on page 243.This edition applies to Version 4 Release

Flushing journal buffersDuring a successful normal shutdown, CICS calls the log manager domain to flushall journal buffers, ensuring that all journal

2. If the default shutdown assist transaction CESD is run, it allows as many tasksas possible to commit or back out cleanly, but within a shorter time

The next initialization of CICS must be an emergency restart, in order to preservedata integrity. An emergency restart is ensured if the next initiali

You are recommended always to use the CESD shutdown-assist transaction whenshutting down your CICS regions. You can use the DFHCESD program “as is”, o

- File control recovery blocks (only if a SHCDSNONRLSUPDATEPERMITTED command has been used).– Transient data queue definitions– Dump table information

If you ever need to redefine and reinitialize the CICS local catalog, you should alsoreinitialize the global catalog. After reinitializing both catalo

and therefore recovery of the most recent units of work cannot be carried out.However, data might be missing from any part of the system log and CICS

Overriding the type of start indicatorThe operation of the recovery manager's control record can be modified byrunning the recovery manager utili

performs the recovery process for work that was in-flight when the previous run ofCICS was abnormally terminated.Recovery of data during an emergency

You can do this by specifying START=INITIAL as a system initialization parameter,or by running the recovery manager's utility program (DFHRMUTL)

ContentsPreface ...viiWhat this book is about ...viiWho should read this book ...viiWhat you need to know to understand this b

Recovery with VTAM persistent sessionsWith VTAM persistent sessions support, if CICS fails or undergoes immediateshutdown (by means of a PERFORM SHUTD

During an emergency restart of CICS, CICS restores those sessions pendingrecovery from the CICS global catalog and the CICS system log to an in-sessio

v If CICS determines that it cannot recover the session without unbinding andrebinding it.The result in each case is as if CICS has restarted followin

You can then start further CICS regions with or without persistent sessions supportas appropriate, provided that you do not exceed the limit for the n

42 CICS TS for z/OS 4.1: Recovery and Restart Guide

Part 2. Recovery and restart processesYou can add your own processing to the CICS recovery and restart processes.This part contains the following sect

44 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 4. CICS cold startThis section describes the CICS startup processing specific to a cold start.It covers the two forms of cold start:v “Startin

– CICS requests the SMSVSAM server, if connected, to release all RLS retainedlocks.– CICS does not rebuild the non-RLS retained locks.v CICS requests

specify on the GRPLIST system initialization parameter. The CSD filedefinition is built and installed from the CSDxxxx system initializationparameters

Journal names and journal models...58Terminal control resources ...58Distributed transaction resources ...59URIMAP definitions and virtual

Transient data resource definitions are installed from Resource groups defined inthe CSD, as specified in the CSD group list (named on the GRPLIST sys

If you define new resource definitions and install them dynamically, ensure thegroup containing the resources is added to the appropriate group list.M

Installable set installThe following VTAM terminal control resources are committed ininstallable sets:v Connections and their associated sessionsv Pip

information saved in the system log from a previous run. The primary andsecondary system log streams are purged and CICS begins writing a new systemlo

52 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 5. CICS warm restartThis section describes the CICS startup processing specific to a warm restart.If you specify START=AUTO, which is the reco

FilesFile control information from the previous run is recovered from informationrecorded in the CICS catalog only.File resource definitions for VSAM

Temporary storageAuxiliary temporary storage queue information (for both recoverable andnon-recoverable queues) is retrieved from the warm keypoint. N

v All intrapartition TD queues are initialized empty.v The queue resource definitions are installed from the global catalog, but they arenot updated b

Autoinstall for programsIf program autoinstall is enabled (PGAIPGM=ACTIVE), program, mapset, andpartitionset resource definitions are installed from t

Input extrapartition data sets ...134Output extrapartition data sets ...135Using post-initialization (PLTPI) programs . . 135Recovery for tempo

Journal names and journal modelsThe CICS log manager restores the journal name and journal model definitionsfrom the global catalog. Journal name entr

v Different TCT from last run. CICS installs the TCT only, and does not apply thewarm keypoint information, effectively making this a cold start for t

60 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 6. CICS emergency restartThis section describes the CICS startup processing specific to an emergency restart.If you specify START=AUTO, CICS d

Any non-RLS locks associated with in-flight (and other failed) transactions areacquired as active locks for the tasks attached to perform the backouts

Reconnecting to SMSVSAM for RLS accessAs on a warm restart, CICS connects to the SMSVSAM server. In additionto notifying CICS about lost locks, VSAM a

Start requestsIn general, start requests are recovered only when they are associated withrecoverable data or are protected and the issuing unit of wor

is successful, but CICS abnormally terminates before the catalog can be updated,CICS recovers the information from the forward recovery records on the

66 CICS TS for z/OS 4.1: Recovery and Restart Guide

Chapter 7. Automatic restart managementCICS uses the automatic restart manager (ARM) component of MVS to increase theavailability of your systems.MVS

Forward recovery logging ...215Forward recovery ...216Recovering VSAM spheres with AIXs ...217An assembler program that calls DFSMS call

If CICS is restarted by ARM with the same persistent JCL, CICS forcesSTART=AUTO to ensure data integrity.Registering with ARMTo register with ARM, you

CANCEL, CICS de-registers from ARM before terminating, because if CICSremained registered, an automatic restart would probably encounter the same erro

CICS START optionsYou are recommended to specify START=AUTO, which causes a warm start after anormal shutdown and an emergency restart after failure.Y

The COVR transactionTo ensure that CICS reconnects to VTAM in the event of a VTAM abend, CICSkeeps retrying the OPEN VTAM ACB using a time-delay mecha

You can also restart a server explicitly using either the server command CANCELRESTART=YES, or the MVS command CANCEL jobname,ARMRESTARTBy default, th

Chapter 8. Unit of work recovery and abend processingA number of different events can cause the abnormal termination of transactions inCICS.These even

See “Commit-failed recovery” on page 83.Backout-failedA unit of work fails while backing out updates to file control recoverableresources. (The concep

terminating transaction takes place immediately. Therefore, it does not cause anyactive locks to be converted into retained locks. In the case of a CI

Intrapartition transient dataIntrapartition destinations specified as logically recoverable are restored bytransaction backout. Read and write pointer

intended for the started task, but does not back out the START request itself.Thus the new task will start at its specified time, but the data will no

PrefaceWhat this book is aboutThis book contains guidance about determining your CICS®recovery and restartneeds, deciding which CICS facilities are mo

Table 1. Effect of RESTART option on started transactions (continued)Description ofnon-terminal STARTcommandEvents Effect ofRESTART(YES)Effect ofRESTA

Backout-failed recoveryBackout failure support is currently provided only by CICS file control.If backout to a VSAM data set fails for any reason, CIC

Transient dataAll updates to logically recoverable intrapartition queues are managed in mainstorage until syncpoint, or until a buffer must be flushed

It might be worth initially deciding to leave a data set online for some timeafter a backout failure, to evaluate the level of impact the failures hav

and issues a console message. If the failure has already been detected by someother (earlier) request, CICS has already started to close the SMSVSAM c

This situation can be resolved only by deleting the rival record with theduplicate key value.Lock structure full errorThe backout required VSAM to acq

distinguishes between a commit failure where recoverable work was performed,and one for which only repeatable read locks were held.Indoubt failure rec

reads against VSAM data sets and has made no updates to other resources, it issafe to force the unit of work using the SET DSNAME or SET UOW commands.

To retrieve information about a unit of work (UOW), you can use either the CEMT,or EXEC CICS, INQUIRE UOW command. For the purposes of this illustrati

When a UOW has been shunted indoubt, CICS retains locks on the recoverableresources that the UOW has updated. This prevents further tasks from changin