Description: Global Resource Serialization (GRS) has enhanced ISGENQ Request=Change processing. Currently a resource owner can only change from Shared control to Exclusive, and only when there are no other Shared owners. This enhancement is to allow an owner to change control from Exclusive down to Shared, providing the opportunity for greater parallelism.
The overall purpose of this enhancement is increased throughput, and the initial exploiter is Batch Modernization.
As with other ISGENQ enhancements, this new function is not being integrated with the older ENQ service, which was essentially functionally stabilized in z/OS® R6. ENQ RET=CHNG requests will continue to function as-is. Also note that ISGENQ will only support changes of global ENQs from Exclusive to Shared when GRS is running in Star mode.
When change was introduced: z/OS V2R1.