CICS / WebSphere

Determining where VSAM data is used: The GENAPP application uses VSAM for various data stores, including the KSDSCUST file. You can use the CICS IA plug-in to the CICS Explorer to create a query to find all the programs that use the KSDSCUST file by transaction ID. The query result lists the programs and associated transactions that use the KSDSCUST file, and how each program accesses the file.

For the batch component of the application, scan the library that contains the Job Control Language (JCL) to identify the batch programs that use the KSDSCUST file.

VSAM to DB2 conversion: You can use the auto-mapping feature of CICS VT to convert the KSDSCUST VSAM file to a DB2 table with the appropriate structure. For complex data structures that require data manipulation, CICS VT provides exit facilities for field-level and record-level re-engineering. You can then use CICS VT and DB2 utilities to move the VSAM data to the new DB2 table.

Testing the conversion: To activate the run-time component of CICS VT in CICS, add appropriate definitions for the CICS VT run-time modules and DB2 definitions to CICS and activate CICS VT for the KSDSCUST table. For batch, change the Data Definition (DD) statements for the KSDSCUST file to point to the VT batch subsystem. When CICS transactions or batch jobs access KSDSCUST, CICS VT intercepts the VSAM request and issues an SQL call to access the new customer DB2 table.

Performance Considerations

IBM CICS Performance Analyzer (CICS PA) for z/OS is an offline historical performance analysis tool that provides detailed reports and views of CICS system and application performance.
Reports include transaction performance reports, reporting for trend analysis and capacity planning, and transaction profiling reports that compare new transaction activity with baseline data. The CICS PA reporting interface lets users tailor these reports and access the most relevant data without needing knowledge of specialized programming languages or the data layout. CICS PA also provides many sample alerts that simplify implementation of alert reporting.

When the GENAPP application runs in a CICSPlex environment, it’s slow when customer agents use the SSC1 transaction. You can use CICS PA to investigate the performance issue:

1. In the Transactions tab of the CICS Explorer, right-click the SSC1 transaction and select Performance history > Response time (see Figure 8). The resulting GENAPP response time chart shows unacceptably high average and peak response times.
2. Right-click a time interval on the chart and select Detail Breakdown. The resulting transaction detail chart shows that transactions spend most of the response time in suspend status.
3. Use the ISPF interface of CICS PA to run a CICS PA Wait Analysis report. The report in Figure 9 shows that terminal input wait and first dispatch time wait are significant parts of the time in suspend status. A reason for high terminal input wait might be that transaction SSC1 isn’t pseudo-conversational and a program needs correction. You can use the CICS IA command flow to identify the program (in this example, LGTESTC1).
4. Use CICS PA Transaction Profiling reports to measure the impact on response time for transaction SSC1 after correcting the program.
5. To identify high first dispatch time waits, view the CICS PA statistics alerts. These waits are caused when the SSC1 transaction runs too slowly and causes backups in the transaction class it runs in (DFHTCL09). CICS PA issues alerts when the statistic exceeds its critical threshold limit (see Figure 10).

You can use CICS PA together with real-time monitors. Use a real-time monitor with alerts active and CICS PA with alerts set to a lower threshold so performance trends are identified before they cause a problem and before the real-time monitor issues an alert.


This article is a shortened version of the IBM Redpaper REDP-4824-00, “Implementation of Popular Business Solutions with CICS Tools,” by Chris Rayns, Eric Higgins, and Peter Siddell.
 

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