Recovery with z/OS Communications Server persistent sessions
With z/OS® Communications Server persistent sessions support, if CICS® fails or undergoes immediate shutdown (by means of a PERFORM SHUTDOWN IMMEDIATE command), the Communications Server holds the CICS LU-LU sessions in recovery-pending state, and they can be recovered during startup by a newly starting CICS region. With multinode persistent sessions support, sessions can also be recovered if the Communications Server or z/OS fails in a sysplex.
- SNPS, single-node persistent sessions
- Persistent sessions support is available, so that Communications Server sessions can be recovered after a CICS failure and restart. This setting is the default.
- MNPS, multinode persistent sessions
- In addition to the SNPS support, Communications Server sessions can also be recovered after a Communications Server or z/OS failure in a sysplex.
- NOPS, no persistent sessions
- Persistent sessions support is not required for the CICS region. For example, a CICS region that is used only for development or testing might not require persistent sessions.
For single-node persistent sessions support, you require z/OS Communications Server V3.4.1 or later, which supports persistent LU-LU sessions. CICS Transaction Server for z/OS, Version 5 Release 4 functions with releases of z/OS Communications Server earlier than V3.4.1, but in the earlier releases sessions are not retained in a bound state if CICS fails. For multinode persistent sessions support, you require z/OS Communications Server V4.R4 or later, and z/OS Communications Server must be in a Parallel Sysplex® with a coupling facility.
CICS support of persistent sessions includes the support of all LU-LU sessions, except LU0 pipeline and LU6.1 sessions. With multinode persistent sessions support, if the Communications Server or z/OS fails, LU62 synclevel 1 sessions are restored, but LU62 synclevel 2 sessions are not restored.