IBM SC34-7012-01 manual Running without persistent sessions support

vIf CICS determines that it cannot recover the session without unbinding and rebinding it.

The result in each case is as if CICS has restarted following a failure without

VTAM persistent sessions support.

In some other situations APPC sessions are unbound. For example, if a bind was in progress at the time of the failure, sessions are unbound.

With multinode persistent sessions support, if a VTAM or z/OS failure occurs and the TPEND failure exit is driven, the autoinstalled terminals that are normally deleted at this point are retained by CICS. If the session is not reestablished and the terminal is not reused within the AIRDELAY interval, CICS deletes the TCTTE when the AIRDELAY interval expires after the ACB is reopened successfully.

Situations in which VTAM does not retain sessions

When VTAM persistent sessions support is in use for a CICS region, in some circumstances VTAM does not retain LU-LU sessions.

vIf you close VTAM with any of the following CICS commands:

–SET VTAM FORCECLOSE

–SET VTAM IMMCLOSE

–SET VTAM CLOSED

vIf you close the CICS node with the VTAM command VARY NET INACT ID=applid.

vIf your CICS system performs a normal shutdown, with a PERFORM SHUTDOWN command.

If single-node persistent sessions support (SNPS), which is the default, is specified

for a CICS region, sessions are not retained after a VTAM or z/OS failure. If

multinode persistent sessions support (MNPS) is specified, sessions are retained

after a VTAM or z/OS failure.

Running without persistent sessions support

VTAM persistent sessions support is the default for a CICS region, but you might

choose to run a CICS region without this support if it is used only for

development or testing. Specify NOPS for the PSTYPE system initialization

parameter to start a CICS region without persistent sessions support. Running

without persistent sessions support can enable you to increase the number of CICS

regions in an LPAR.

If you have a large number of CICS regions in the same LPAR (around 500), with

persistent sessions support available for all the regions, you might reach a z/OS

limit on the maximum number of data spaces and be unable to add any more

CICS regions. In this situation, when you attempt to start further CICS regions,

you see messages IST967I and DFHSI1572, stating that the ALESERV ADD request

has failed and the VTAM ACB cannot be opened. However, a region without

persistent sessions support does not use a data space and so does not count

towards the limit. To obtain a greater number of CICS regions in the LPAR:

1. Identify existing regions that can run without persistent sessions support.

2. Change the PSTYPE system initialization parameter for those regions to specify

NOPS, and specify a zero value for the PSDINT system initialization parameter.

3. Cold start the regions to implement the change.

40CICS TS for z/OS 4.1: Recovery and Restart Guide