IBM OS manual Detailed affinity analysis, Enqueue/Dequeue

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Detailed affinity analysis

Each of the above command scenarios is dealt with below. A description of how the use of the command appears in the Transaction Affinities Utility Reporter report is given, followed by an assessment of any affinity problem it causes. However, it would be helpful ®rst to expand on the structure of a CSP segmented application.

The default CICS transaction identi®er that CSP provides for applications is XSPS, although this is normally replaced by a unique transid for the application concerned. CSP transactions are de®ned so that the initial program is DCBINIT or DCBRINIT, the former for the ®rst segment (that is, the ®rst transaction in a pseudoconversation), the latter for subsequent segments. These two CSP programs ensure that the correct environment is built for the application, including loading of programs and tables and saving and restoring of state data. DCBINIT and DCBRINIT branch to other CSP programs, but these other programs are not known to CICS. This means the Transaction Affinities Utility Reporter report shows DCBINIT or DCBRINIT as the program containing the affinity command, but the command offset is the generic x'FFFFFFFF'. In fact, the CSP program that issues most EXEC CICS commands is DCBMODS.

It is very important to note that a single report transaction/program/offset entry can conceal several affinity commands. Although the Transaction Affinities Utility Detector has correctly logged, and deduced information from, all the commands, it is only the ®rst one encountered that is described in full in the report. So the Transaction Affinities Utility may report DCBINIT issuing only ENQUEUEs, but in reality DCBMODS is issuing both ENQUEUEs and DEQUEUEs. Similarly, the Transaction Affinities Utility may report that DCBINIT is issuing only WRITEQ TS commands, but in reality DCBMODS is issuing READQ TS and DELETEQ TS as well. (The Transaction Affinities Utility Scanner shows that this is indeed the case when it is run against the CSP/AE load library.)

Note that there is a unique generic offset for each different command type within an affinity group. The generic offset is zero minus the group/function code for the command. So, for example, ENQUEUEs appear with x'FFFFEDFC', and DEQUEUEs appear with x'FFFFEDFA'. This is also the case for other command types.

ENQUEUE/DEQUEUE

There is an EQ affinity group in the report for each table or application or map that is loaded. The resource used in each case starts with 'FZE' and contains the name of the load module concerned. Other resources that may appear are 'FZELOAD' and 'FZETUTRI'. The programs involved are DCBINIT and DCBRINIT.

Upon analysis, this use of ENQUEUE/DEQUEUE does not cause affinity. Here, the ENQUEUE/DEQUEUE is being used to serialize a browse on an ALF, so that another CSP application in the same CICS region does not interfere with the loading process. If multiple CICS regions were cloned, each cloned CICS region must perform this same loading process, but this has no effect on any of the other CICS regions. So the ENQUEUE/DEQUEUE is not CICSplex wide and does not cause affinity. All that is required is to ensure that each CICS has access to the ALFs. Because these are used read-only by CSP/AE, the ALFs may be shared without resorting to the overhead of function shipping.

Chapter 6. Running the Reporter 51

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Contents IBM Page IBM Third edition March Contents Appendix A. Details of what is detected Reporter output Scanner output Examples Vi Cics Transaction Affinities Utility Guide Vii Trademarks Preface Argument zero Cics Transaction Server for OS/390 BibliographyCics books for Cics Transaction Server for OS/390 Other Cics books CICSPlex SM books for Cics Transaction Server for OS/390Summary of changes Xiv Cics Transaction Affinities Utility Guide Affinities, see the Cics Application Programming Guide Introducing transaction affinitiesRouting region Requesting regionTarget region What does dynamic routing cost? Benets of dynamic routingTransaction affinities Global Inter-transaction affinityTransaction-system affinity Affinity relationsCics programming techniques for transaction affinity Affinity lifetimesAvoiding the effects of transaction affinity Safe programming techniquesUnsafe programming techniques Suspect programming techniquesProtecting applications from one another What next? Important note Introducing the Transaction Affinities UtilityAffinity utility program components Commands detected by the Transaction Affinities Utility Detector component Scanner componentDetector components What is detectedWorsening of transaction affinities relations What is not detectedHow the affinity data is collected Controlling the DetectorSaving affinity data Control record Vsam le Affinity data Vsam lesReport presenting the affinity data in a readable form Detector performanceReporter component Builder componentIntroducing the Transaction Affinities Utility Cics Transaction Affinities Utility Guide Creating the Vsam les Preparing to use the affinity utility programEstimating the size of the MVS data space and Vsam les #termids Dening the Vsam les to CicsPreparing to use the affinity utility program Cics Transaction Affinities Utility Guide Creating a summary report Running the ScannerAffmod DD statement Cics Transaction Affinities Utility Creating a detailed reportContents of a detailed report Is an example of a detailed report produced by the Scanner Cics Transaction Affinities Utility Guide Changing the state Running the DetectorChanging the options CAFF01 Displaying the Detector control screenStarting the collection of affinity data When you can start collecting affinity dataResuming the collection of affinity data Pausing the collection of affinity dataWhen you can pause affinity data collection When you can resume collecting affinity dataStopping the collection of affinity data When you can stop collecting affinity dataCAFF02 Changing the Detector options„1… The control options Perform periodic saves Restore data on start„2… Detect affinity types „4… Last update by useridSize of dataspace Transid prexDetector errors Cics Transaction Affinities Utility Guide Caucntl DD statements Running the ReporterRequesting a report from the Reporter CAUAFF1, CAUAFF2, and CAUAFF3 DD statementsCmdgrps DD statement Output from the ReporterTrangrps DD statement System Affinity reportTrangroup „1… Incorrect affinity types„2… Affinity types reported „3… Affinities reportsLifetime RecoverableCommand AffinityTotal Transactions Producing affinity transaction group denitionsTerminal BTS TaskAfflifesystem Descaddress CWA Using the affinity reportRemove affinity relation worsening Understanding the affinitiesModifying affinity transaction groups Remove false affinitiesCompressing affinity data Shared storage Using the IBM Cross System ProductSPI commands ENQUEUEs/DEQUEUEsENQUEUE/DEQUEUE Detailed affinity analysisGetmain Shared SPI commands Cics Transaction Affinities Utility Guide DSPSIZE=16number Running the BuilderCONTEXT=plexname Repgrps DD statement Syntax for input to the BuilderAffgrps DD statement Builder input syntax Output from the Builder Header statementsCombined affinity transaction group denitions Combining basic affinity transaction groups Relation a Relation B Resultant relation C Empty transaction groups report Data sets processed reportGroup merge report Sample group merge report Error reportSample error report Cics Transaction Affinities Utility Guide ENQ/DEQ Appendix A. Details of what is detectedLoad HOLD/RELEASE TS commandsAddress CWA CANCEL/DELAY/POST/START Wait commands SPI commandsCics Transaction Affinities Utility Guide Scanner output Reporter outputExamples Example 2±VS Cobol Which occurs for the rst Move Move Cobol affinities Logon or System when Pconv expectedUnrecognized Transids Cics Transaction Affinities Utility Guide Detector table manager diagnostics Appendix D. DiagnosticsFunction code values Table identier values Reason code values This section Detector Cafb request queue manager diagnosticsDate formatter diagnostics Reason code valuesIndex Bappl Vsam Cics Transaction Affinities Utility Guide Sending your comments to IBM Ibmr IBM

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