IBM SC34-7012-01 manual Cold start, Recovery of data during an emergency restart

performs the recovery process for work that was in-flight when the previous run of CICS was abnormally terminated.

Recovery of data during an emergency restart

During the final stage of emergency restart, the recovery manager uses the system log data to drive backout processing for any units of work that were in-flight at the time of the failure. The backout of units of work during emergency restart is the same as a dynamic backout; there is no distinction between the backout that takes place at emergency restart and that which takes place at any other time.

The recovery manager also drives:

vThe backout processing for any units of work that were in a backout-failed state at the time of the CICS failure.

vThe commit processing for any units of work that were in a commit-failed state at the time of the CICS failure.

vThe commit processing for units of work that had not completed commit at the time of failure (resource definition recovery, for example).

The recovery manager drives these backout and commit processes because the condition that caused them to fail may be resolved by the time CICS restarts. If the condition that caused a failure has not been resolved, the unit of work remains in backout- or commit-failed state. See “Backout-failed recovery” on page 79 and “Commit-failed recovery” on page 83 for more information.

For more information about the emergency restart process, see Chapter 6, “CICS emergency restart,” on page 61.

Cold start

On a cold start, CICS reconstructs the state of the region from the previous run for remote resources only. For all resources, the region is built from resource definitions specified on the GRPLIST system initialization parameter and those resources defined in control tables.

The following is a summary of how CICS uses information stored in the global catalog and the system log on a cold start:

vCICS preserves, in both the global catalog and the system log, all the information relating to distributed units of work for partners linked by:

–APPC

–MRO connections to regions running under CICS Transaction Server

–The resource manager interface (RMI); for example, to DB2 and DBCTL.

vCICS does not preserve any information in the global catalog or the system log that relates to local units of work.

Generally, to perform a cold start you specify START=COLD, but CICS can also force a cold start in some circumstances when START=AUTO is specified. See the CICS System Definition Guide for details of the effect of the START parameter in conjunction with various states of the global catalog and the system log.

An initial start of CICS

If you want to initialize a CICS region without reference to the global catalog from a previous run, perform an initial start.

36CICS TS for z/OS 4.1: Recovery and Restart Guide