Resource contention can result in less important work holding resources that are needed by more important work. To prevent this, ENQ and Latch contention processing issue an SRM ENQHOLD SYSEVENT to promote the work holding the resource. The installation uses the enqueue residence value (ERV) on the IEAOPTxx parmlib member to alter the amount of CPU service units that an address space or an enclave is allowed to absorb when it is causing contention. During this time, the work unit runs with increased dispatching priority.

Because a DASD RESERVE can also cause hardware contention, but not an ENQ contention, global resource serialization always issues an SRM ENQHOLD SYSEVENT against authorized programs that reserve a DASD device. Global resource serialization cannot know if there is a hardware contention because the associated RESERVE ENQ is usually excluded to a SYSTEM scope and there could be a waiter on another system that is sharing the DASD.

See Checking for ENQ contention problems to determine how to find ENQs and GRS-managed latches that are in contention.