OTMA fast transaction pipe checkpoint cleanup (FASTTPCU)

When the FASTTPCU parameter is activated in the DFSOTMA descriptor, IMS removes OTMA transaction pipes (tpipes) in an IMS system after they have been idle for two consecutive system checkpoints.

If the IMS system does not specify the FASTTPCU parameter in the DFSOTMA statement, or the parameter is not activated, the default clean up of idle OTMA tpipes is performed after three consecutive checkpoints.

The FASTTPCU settings in a shared queues environment

In a shared queues environment, if you activate the FASTTPCU parameter in the front-end IMS system, the behavior could vary in the back-end IMS system. Because the FASTTPCU parameter applies only to IMS 15.3 and later versions, the number of checkpoints for removing idle tpipes could be different depending on:

the versions of the front-end IMS system and the back-end IMS system
the installation of APAR PH52141 in the back-end IMS system

If both the front-end IMS system and the back-end IMS system are in IMS 15.3, and the back-end IMS system has APAR PH52141 applied, the back-end IMS system inherits the FASTTPCU setting from the front-end IMS system for any OTMA tpipes generate for the work from the front-end IMS system. This overwrites any FASTTPCU setting in the back-end IMS system.

If the back-end IMS system is in IMS 15.2 or lower versions, the following table provides information about how many checkpoints it takes to remove idle tpipes in a shared queues environment in different cases:

Table 1. The number of checkpoints for removing idle otma tpipes
	Front-end IMS system in IMS 15.2 or lower versions	Front-end IMS system in IMS 15.3 or higher versions
Back-end IMS system with APAR PH52141 applied	Front-end IMS: 3 checkpoints Back-end IMS: 3 checkpoints	Front-end IMS: 2 checkpoints Back-end IMS: 2 checkpoints
Back-end IMS system without APAR PH52141 applied	Front-end IMS: 3 checkpoints Back-end IMS: 3 checkpoints	Front-end IMS: 2 checkpoints Back-end IMS: 3 checkpoints

Important: While you can clean up inactive tpipes faster than before with the FASTTPCU function, the performance of your IMS systems could remain unchanged.