Reviewing z/OS® parameter settings

There are several SRM/WLM options that allow you to control how work is assigned between zIIPs and standard CPs. zIIP-eligible work may also execute on standard CPs in order to achieve workload goals.

Parmlib member IEAOPTxx contains the IIPHONORPRIORITY statement which controls the workflow to zIIPs. If you specifiy IIPHONORPRIORITY=YES this indicates that standard CPs may execute zIIP-eligible and non-zIIP-eligible work in priority order, if zIIP processors are unable to execute all zIIP-eligible work. This is the default.

Specifying IIPHONORPRIORITY=NO means that standard processors will not process zIIP processor eligible work unless it is necessary to resolve contention for resources with non-zIIP processor eligible work.

If you specify NO for Honor Priority when defining a service class, work in this service class does not receive help from regular CPs when there is insufficient zAAP or zIIP capacity for the workload in the system, regardless of the setting for IIPHONORPRIORITY in parmlib member IEAOPTxx. Regular CPs may still help when it is necessary to resolve contention for resources with regular CP work.

See z/OS MVS Initialization and Tuning Reference for more information on the parmlib member IEAOPTxx.