IMS message queue data set size and OTMA

Messages entering IMS from OTMA contain both the OTMA message prefix and other existing IMS message prefixes.

The OTMA message prefix is variable in length. Excluding the user data section, the OTMA message prefix can become very large, sometimes over 200 bytes in length. The OTMA message prefix, including the user data section, is stored on IMS message queue data sets, which increases usage of the queue buffer pool.

Tip: Because of this increase in queue buffer pool usage, try to increase the size of the message queue data sets.

If the security-data section of the OTMA message prefix contains network security credentials, the size of the OTMA message can increase by up to 504 bytes. Therefore, consider increasing the size of the SHMSG and LGMSG message queue data sets and the size of the message queue pool.