MaxUncommittedMsgs (MQLONG)

This is the maximum number of uncommitted messages that can exist within a unit of work. The number of uncommitted messages is the sum of the following since the start of the current unit of work:

  • Messages put by the application with the MQPMO_SYNCPOINT option
  • Messages retrieved by the application with the MQGMO_SYNCPOINT option
  • Trigger messages and COA report messages generated by the queue manager for messages put with the MQPMO_SYNCPOINT option
  • COD report messages generated by the queue manager for messages retrieved with the MQGMO_SYNCPOINT option
The following messages are not counted as uncommitted:

  • Messages put or retrieved by the application outside a unit of work
  • Trigger messages or COA/COD report messages generated by the queue manager as a result of messages put or retrieved outside a unit of work
  • Expiration report messages generated by the queue manager (even if the call causing the expiration report message specified MQGMO_SYNCPOINT)
  • Event messages generated by the queue manager (even if the call causing the event message specified MQPMO_SYNCPOINT or MQGMO_SYNCPOINT)
Note:
  1. Exception report messages are generated by the Message Channel Agent (MCA), or by the application, and are treated in the same way as ordinary messages put or retrieved by the application.
  2. When a message or segment is put with the MQPMO_SYNCPOINT option, the number of uncommitted messages is incremented by one regardless of how many physical messages actually result from the put. (More than one physical message might result if the queue manager must subdivide the message or segment.)
  3. When a distribution list is put with the MQPMO_SYNCPOINT option, the number of uncommitted messages is incremented by one for each physical message that is generated. This can be as small as one, or as great as the number of destinations in the distribution list.

The lower limit for this attribute is 1; the upper limit is 999 999 999. The default value is 10000.

To determine the value of this attribute, use the MQIA_MAX_UNCOMMITTED_MSGS selector with the MQINQ call.