DEQ_EVENTQ: Retrieving Events from the Event Queue

Use the DEQ_EVENTQ request to read and dequeue queued events from a user's event queue. You can read and dequeue multiple EMCs from your event queue with a single invocation of the DEQ_EVENTQ command. Each set of read and dequeue operations is done atomically. Once dequeued from the event queue, an EMC is not deleted. The EMC remains associated with the user and the sublist for which it was created until the user deregisters its interest in monitoring the sublist or the user disconnects or fails.

List services return the event monitor controls (EMC) objects in a storage area you specify with either the BUFFER or BUFLIST parameter. Each of the EMCs returned in the BUFFER or BUFLIST area is mapped by the IXLYEMC macro and contains the following information:

The connection identifier
The list number of the list header containing the sublist
The list entry key of the sublist
The user notification controls — 16 bytes of user-defined data

List services returns the EMCs in the BUFFER or BUFLIST storage area in the order in which they are queued to the event queue, with the oldest transitions first and the most recent transitions last.

The DEQ_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 retrieving events from an event queue.