Buffer pool enhancements
IBM MQ for z/OS uses memory, known as buffer pools, as the primary location for message storage. The buffer pools are backed up by Virtual Storage Access Method (VSAM) files known as page sets. Page sets are used for long term message storage or in the event that a buffer pool cannot hold all the messages for the queues defined to use the buffer pool. This two-stage storage avoids I/O as much as possible for short-lived messages.
Note: Avoiding buffer pool to page set I/O is a separate process and might be done for ...