IBM SC34-7012-01 Specifying a JOURNALMODEL resource definition, Without a JOURNALMODEL definition

CICS log manager connects to its log stream automatically during system initialization, unless it is defined as TYPE(DUMMY) in a CICS JOURNALMODEL resource definition.

Although the CICS system log is logically a single logical log stream, it is written to two physical log streams—a primary and a secondary. In general, it is not necessary to distinguish between these, and most references are to the system log stream. Using a primary and a secondary log stream for its single system log enables CICS to optimize its use of log stream storage through its process of moving long-running UOWs from the primary to secondary logstreams.

Specifying a JOURNALMODEL resource definition

During a cold start, and a warm and emergency restart, CICS retrieves the names of its system log streams from the global catalog, ensuring that it reconnects to the same log streams that were used on the previous run.

During an initial start, CICS uses default log stream names, unless you specify otherwise on a JOURNALMODEL resource definition. The process of selecting and connecting to a system log stream is as follows:

Without a JOURNALMODEL definition

If CICS can't find a JOURNALMODEL resource definition for DFHLOG and DFHSHUNT, it issues calls to the MVS system logger to connect to its system log streams using default names. These are:

region_userid.applid.DFHLOG region_userid.applid.DFHSHUNT

where region_userid is the RACF® user ID under which the CICS address space is running, and applid is the region's VTAM APPL name (taken from the APPLID system initialization parameter). The CICS-supplied JOURNALMODEL definitions for default DFHLOG and DFHSHUNT log streams are in the CSD group DFHLGMOD, which is included in DFHLIST.

If you use these default log stream names, ensure that

vThe default log streams are defined explicitly to the MVS system logger, or

vSuitable model log streams are defined for dynamic creation.

With a JOURNALMODEL definition

If CICS finds a JOURNALMODEL definition with JOURNALNAME(DFHLOG) and JOURNALNAME(DFHSHUNT), it issues calls to the MVS system logger to connect to the system log streams named in the definitions. Ensure that the system log stream names are unique to the CICS region.

If you define JOURNALMODEL resource definitions for your system logs, ensure that:

vThe log streams named in the JOURNALMODEL are defined to the MVS system logger, or

vSuitable model log streams are defined that enable them to be created dynamically.

If you don't want to use a system log (for example, in a CICS test region), specify JOURNALMODEL resource definitions for DFHLOG and DFHSHUNT with TYPE(DUMMY). Note that running CICS with the system log defined as TYPE(DUMMY) forces you to perform an initial start, and CICS does not support dynamic transaction backout.

Chapter 11. Defining system and general log streams 109