Streaming queues is a feature introduced to MQ for z/OS with version 9.3.0 that allows a copy of messages to be sent to a secondary queue without affecting the original messages. Streaming queues can be setup to always copy the messages no matter what using “MUSTDUP” (must duplicate) or to copy all of the messages it can without any disruption to the original flow of messages by using “BESTEF” (best effort). Streaming queues are useful for a variety of scenarios such as analysis, data recovery testing and development, and also for event message consumption. More information about streaming queues can be found here: https://www.ibm.com/docs/en/ibm-mq/9.3?topic=scenarios-streaming-queues

Updates added with the release of 9.3.2 will allow the use of streaming queues to be monitored easily using System Management Facility (SMF) accounting data. Before the updates added in 9.3.2 it could be difficult to tell if and how much streaming had occurred - there were signs such as a doubling in pages old and new for every streamed message and an increase in put average cpu time when both compared to put count but in a complex system with lots of moving parts and without identical sample data this could be hard to spot. Additional information on SMF Accounting Data in relation to streaming queues can be found here: https://www.ibm.com/docs/en/ibm-mq/9.3?topic=data-thread-level-queue-level-records

Luckily in the recently released 9.3.2 streaming queues now has a datapoint in the CSQDWQ control block called streamedN that counts the number of streams that occurred, and an addition to MP1B to display the number of streamed messages. With the newly added datapoint the number of streamed messages can now be tracked allowing for a better understanding of what is going on and when streaming is occurring without a super in-depth knowledge of MQ accounting data. This update as well as other new features are described on the What's new in IBM MQ 9.3.2 page here: https://www.ibm.com/docs/en/ibm-mq/9.3?topic=932-whats-new-in-mq

If you have any questions about the above, feel free to get in contact with me via email at johnny.murphy@ibm.com