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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.
v If CICS does not restart within the persistent sessions delay interval, as specified
by the PSDINT system initialization parameter.
v If you perform a COLD start after a CICS failure.
v If CICS restarts with XRF=YES, when the failed CICS was running with
XRF=NO.
v If CICS cannot find a terminal control table terminal entry (TCTTE) for a session;
for example, because the terminal was autoinstalled with AIRDELAY=0
specified.
v If a terminal or session is defined with the recovery option (RECOVOPTION) of
the TYPETERM or SESSIONS resource definition set to RELEASESESS,
UNCONDREL or NONE.
v If a connection is defined with the persistent sessions recovery option
(PSRECOVERY) of the CONNECTION resource definition set to NONE.
Chapter 3. Shutdown and restart recovery 39