Planning for WLM

This section provides some instructions to help you determine the extent to which you can use CICSPlex® SM’s workload management in your enterprise.

Workload balancing or workload separation?

Workload balancing should be used wherever possible because it makes the best use of the available CICS® systems, and provides opportunities for increased throughput and performance.

Workload separation (by process type, user, terminal, and transaction) should be implemented only where strictly necessary, because it prevents full exploitation of CICSPlex SM’s workload balancing functions. If you have defined more than one CICSplex, and have made the division to reflect use of CICS systems by different groups of users, for example, it’s possible that you will be able to use simple workload balancing rather than workload separation within the CICSplex. For example, if you have separated the CICS systems used by group A from the CICS systems used by group B by defining two CICSplexes, then within each CICSplex you can implement workload balancing. If you haven’t taken this approach, you might consider it necessary to recognize such groupings by implementing workload separation.

There are two major activities in your planning for WLM:

Identifying the workloads

Begin by identifying the workloads processed in your enterprise. These are certain to be apparent in any underlying TOR-AOR-FOR configurations that existed prior to your interest in CICSPlex SM. Next, confirm that the current CICSPlex SM configuration of CICS systems supports the identified workloads. In particular:

Identifying intertransaction affinities

Intertransaction affinities, which require related transactions to be processed by the same target region, prevent optimum workload distribution. In general, they arise either because of the way in which one transaction passes data to another, or because of a requirement to coordinate the processing of two or more transactions. Identifying affinities isn’t always easy, but there are some methods you can use. For example, you can review application design documentation or source code; you can run CICStraces; or you can use the Start of changeIBM® CICS Interdependency Analyzer for z/OSEnd of change. For a detailed discussion of intertransaction affinities and ways of identifying them, see the CICS/ESA publication Dynamic Transaction Routing in a CICSplex.

Having identified any affinities in a workload, you should make every attempt to remove them. If you cannot remove them completely, gauge the duration of the affinity and try to minimize it. You can define an intertransaction affinity to CICSPlex SM as lasting:

Be aware that CICSPlex SM must honor an active affinity: if an affinity is active but the target region becomes unavailable, the transaction isn’t routed. In the case of a BTS transaction, BTS will wait for the region to start.

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