Region status server, bottom-tier parameter (BOTRSUPD)

BOTRSUPD={1|number}

For sysplex optimized workloads, the BOTRSUPD value is converted from a task load percentage to a real task count. That count is used to define the bottom-tier task load range, from zero up to this value.

The value range is from 1 - 25. When the task load for a region falls within this range, the task load is then broadcast to the coupling facility (CF) for every change in the task load. When the load reaches this value, the RS server update frequency task rules are activated.

The default value of the BOTRSUPD parameter is 1%.

Change this value only after considering the impact that the change might have on your workload and coupling facility throughput. The BOTRSUPD parameter provides a smoother distribution of the workload during periods of low throughput. When your CICSplex consists of many target regions and you increase this value too much, you risk overloading the CF with update requests, which can result in degraded WLM and general z/OS subsystem performance.

When you need to modify the BOTRSUPD value, ensure that you monitor the performance of your coupling facility and WLM throughput capabilities for at least several days after modification.

Disabling updates to the CF due to BOTRSUPD

You can set the following feature toggle to disable updates to the CF when the task load falls below the lower tier threshold:

com.ibm.cics.cpsm.wlm.botrsupd.enabled=false

The lowest possible setting for BOTRSUPD is 1%. Therefore, regions with a high MXT setting, which spend a significant amount of time operating below 1% of their declared capacity, might perform a high number of CF updates. With this feature toggle in effect, when the task load for a region falls within the BOTRSUPD range, no updates are made to the CF. The task load value stored in the CF will remain zero until the first task load boundary defined by the UPDATERS parameter is reached.

Note that if only a subset of target regions within a workload are run with com.ibm.cics.cpsm.wlm.botrsupd.enabled=false, then those regions might take a greater proportion of the workload.

See Specifying feature toggles for instructions on how to specify feature toggles in your region configuration.