The event queue monitoring function allows you to determine whether your event queue in the structure is empty (contains no event monitor controls objects (EMCs)) or non-empty (contains one or more EMCs) without incurring the overhead of accessing the coupling facility. As with list monitoring, the event queue monitoring function uses a list notification vector allocated in high-speed processor storage. The system maintains event queue state information in the list notification vector. As with the list monitoring function, you can choose to be informed of the event queue's transitions to a non-empty state by means of a list transition exit or through your own polling mechanism.

The MONITOR_EVENTQ request type is valid only for a keyed list structure allocated in a coupling facility with CFLEVEL=3 or higher.

See also IXLLSTC for information about event queue monitoring.