Effect of the z/OS WLM health service on CICSPlex SM workload routing
In a CICS® region, if the z/OS® Workload Manager (z/OS WLM) health service is active, CICSPlex® SM WLM takes account of the region's z/OS WLM health state in the routing decision.
For CICSPlex SM WLM to take into account the z/OS WLM health state of the target regions, the following conditions apply:
- Both the routing and target regions must be at a minimum of CICS TS V5.4 (CICS and CICSPlex SM libraries); otherwise, the z/OS WLM health state will be ignored, and the target regions are deemed as ready to receive work.
- The z/OS WLM health service must be enabled in the CICS region. It is enabled by default. If the service is disabled, the region is also deemed as ready to receive work. To activate this service, you must set the WLMHEALTH system initialization parameter.
How the z/OS WLM health state of CICS regions affects CICSPlex SM routing decisions
The z/OS WLM health state of a region is reflected by a z/OS WLM health value in the range 0 - 100. When deciding where to route work, CICSPlex SM WLM might assign an additional weight in the routing algorithm for the target region, based on its health value:
- If the target region has a z/OS WLM health value of zero, it is not eligible to receive work. CICSPlex SM WLM will not route work to this region. Any workload affinities that are associated with this region will remain and be honored; however, workload routing based on those affinities will fail while the health value is zero, and will result in either message EYUWR0003W or a SYSIDERR condition. Message EYUWR0003W indicates that the EYU9WRAM program was in effect and the affinity AOR was not available. To resolve such routing failures, initiate a warm-up for the region so that the health value is non-zero, and then rerun your workload. See Initiating a CICS system warm-up.
- For any target region with a health value between 1 and 99, CICSPlex SM WLM assigns an additional weight in the routing algorithm, based on the health value. The greater the health value, the lower the weight, which makes this region more favorable in the routing decision. Likewise, the lower the health value, the greater the weight, which reduces the chances of this region to receive more work. Note that a region that is assigned a high additional weight remains active and might still receive work if no other healthier regions are available in the same scope.
- When a target region has a health value of 100, no additional weight is assigned.
During the CICS warm-up or cool-down process, CICS adjusts the z/OS WLM health value of the region. As a result, this affects the routing decision of CICSPlex SM WLM, which restricts workload into the region during that process. In general, when a region is warming up, its health value increases periodically, and the region might gradually receive a larger workload; when a region is cooling down, its health value decreases periodically, and the region might gradually receive less work until it becomes ineligible as a target. For more information about what happens during CICS warm-up or cool-down, see CICS warm-up and cool-down by use of z/OS Workload Manager health service.
Making a region ineligible as a workload routing target
You can deliberately make a region ineligible as a workload routing target in CICSPlex SM routing decisions by setting its z/OS WLM health open status to
CLOSE in the
MVS workload management (MVSWLM) view. This will gradually make the region
less favorable until the region's z/OS WLM heath value drops to 0, indicating that the region
becomes ineligible. Additionally, you can change a region's z/OS WLM heath value to zero
immediately, by setting its z/OS WLM health open status to