APPC connection quiesce processing

When an APPC parallel-session connection with a CICS® Transaction Server for z/OS® region is shut down normally, CICS exchanges information with its partner to discover if there is any possibility that resynchronization is required when the connection is restarted.

This exchange is known as the connection quiesce protocol (CQP).

CICS determines that resynchronization is not required if all the following conditions are true:

The connection is being shut down.
There are no user sessions active (the CQP uses the SNASVCMG sessions). If the SNASVCMG sessions become inactive before the user sessions, the CQP will not take place.
The CICS recovery manager domain has no record of outstanding syncpoint work or resynchronization work for the connection.

Once the CQP has completed, CICS ensures that no recoverable work can be initiated for the connection until a fresh logname exchange has taken place.

If the CQP determines that resynchronization is not required, CICS:

Sets the connection's recovery state to NORECOVDATA
If CICS is a member of a generic resource group, ends any affinity held by z/OS Communications Server and issues a message to say that the affinity has been ended.

If there is any failure of the CQP, CICS presumes that there is a possibility of resynchronization being necessary. You may use the procedures described here to determine if this is truly the case, and perform the necessary actions manually. Alternatively, you can reacquire the connection and release it again, to force CICS to re-attempt the CQP.

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Last updated: Thursday, 27 June 2019