You can use the list transition exit to monitor lists and/or your event queue. See MONITOR_EVENTQ: Monitoring an Event Queue for information about event queue monitoring. In either case, whether you use the list transition exit to monitor multiple lists, your single event queue, or both, it is important to understand the relationship between your list transition exit and the object(s) it is monitoring.

If you use a list notification exit to monitor multiple objects, note that the exit is given control whenever any object you monitor this way changes from empty to nonempty. To determine which monitored object triggered the notification, use the IXLVECTR macro with either the TESTLISTSTATE or LTVECENTRIES parameter to check the vector entry for each candidate object.

During structure rebuild, the list transition exit is not given control. When the rebuild completes, either normally or because of a rebuild stop, the list transition exit is given control once to inform you of any list transition transitions that might have occurred during the rebuild. This is done whether or not you are currently monitoring any lists or your event queue.