Sysplex optimized workload routing overview

Sysplex optimized workload routing is enabled at the z/OS® coupling facility (CF) level by a region status (RS) server. With CICS Explorer®, you can monitor the distribution of dynamic workloads through your CICSplex.

When a target region is running in sysplex optimized mode, the target region maintains the task count using the CICS® transaction manager. The count includes all tasks in the CICS region, not just those that are dynamically routed. The load value for the CICS region, with its basic health status, is periodically broadcast to the coupling facility, where it is available for interrogation by other CICS regions, CMASs and other CICS address spaces. If region status data is available, CICSPlex® SM uses the data when it makes its dynamic routing decision.

For sysplex optimized workloads, routing regions review the same status data in the CF for a potential target region regardless of which CMAS manages it. As a result, the routing region is using status data that might be updated many times a second to evaluate a target region, rather than status data that might be up to 15 seconds old (as would be the case in non-optimized mode). The refresh interval can vary from 2 seconds down to 1 millisecond. In an environment where all routing targets are in similar health and connectivity states, the spread of work across the workload target scope is more accurately distributed according to the selected workload algorithm than in non-optimized mode.

If the CF is not available, workload routing returns to non-optimized mode.

Benefits of sysplex optimized workload routing

Sysplex optimized workload routing is recommended for all workloads. Where the workload router and target regions span more than one sysplex, the benefits of optimized routing are reduced as region status data stored in the z/OS Coupling Facility (CF) is not shared across sysplexes. If possible, routers and targets for a workload should reside on the same sysplex.

Sysplex optimized workload routing provides the following benefits:
  • Removal of the impact of workload batching.
  • Higher workload throughput due to reduced or no queueing of work in CICS regions that have already reached the MXT limit.
  • Increased confidence that workload spikes will be smoothed out quickly across available target regions.
  • With CICS TS 5.4 or higher, support for z/OS WLM Health in the CICS region status data records shared with the CF, allowing for almost immediate indications that target regions should no longer be selectable.