During an emergency restart of CICS, CICS restores those sessions pending recovery from the CICS global catalog and the CICS system log to an in-session state. This process of persistent sessions recovery takes place when CICS opens its VTAM ACB. With multinode persistent sessions support, if VTAM or z/OS fails, sessions are restored when CICS reopens its VTAM ACB, either automatically by the COVR transaction, or by a CEMT or EXEC CICS SET VTAM OPEN command. Although sessions are recovered, any transactions inflight at the time of the failure are abended and not recovered.

When a terminal user enters data during persistent sessions recovery, CICS appears to hang. The screen that was displayed at the time of the failure remains on display until persistent sessions recovery is complete. You can use options on the TYPETERM and SESSIONS resource definitions for the CICS region to customize CICS so that either a successful recovery can be transparent to terminal users, or terminal users can be notified of the recovery, allowing them to take the appropriate actions.

If APPC sessions are active at the time of the CICS, VTAM or z/OS failure, persistent sessions recovery appears to APPC partners as CICS hanging. VTAM saves requests issued by the APPC partner, and passes them to CICS when recovery is complete. When CICS reestablishes a connection with VTAM, recovery of terminal sessions is determined by the settings for the PSRECOVERY option of the CONNECTION resource definition and the RECOVOPTION option of the SESSIONS resource definition. You must set the PSRECOVERY option of the CONNECTION resource definition to the default value SYSDEFAULT for sessions to be recovered. The alternative, NONE, means that no sessions are recovered. If you have selected the appropriate recovery options and the APPC sessions are in the correct state, CICS performs an ISSUE ABEND to inform the partner that the current conversation has been abnormally ended.

If CICS has persistent verification defined, the sign-on is not active under persistent sessions until the first input is received by CICS from the terminal.

The CICS Resource Definition Guide describes the steps required to define persistent sessions support for a CICS region.

Situations in which sessions are not reestablished

When VTAM persistent sessions support is in use for a CICS region, CICS does not always reestablish sessions that are being held by VTAM in a recovery pending state. In the situations listed here, CICS or VTAM unbinds and does not rebind recovery pending sessions.

vIf CICS does not restart within the persistent sessions delay interval, as specified by the PSDINT system initialization parameter.

vIf you perform a COLD start after a CICS failure.

vIf CICS restarts with XRF=YES, when the failed CICS was running with XRF=NO.

vIf CICS cannot find a terminal control table terminal entry (TCTTE) for a session; for example, because the terminal was autoinstalled with AIRDELAY=0 specified.

vIf a terminal or session is defined with the recovery option (RECOVOPTION) of the TYPETERM or SESSIONS resource definition set to RELEASESESS, UNCONDREL or NONE.

vIf a connection is defined with the persistent sessions recovery option (PSRECOVERY) of the CONNECTION resource definition set to NONE.

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IBM SC34-7012-01 manual Situations in which sessions are not reestablished