Mapping log streams

Except for VSAM RLS forward recovery log stream names, which are obtained directly from the VSAM catalog, CICS® maps the system log name or journal name to a corresponding log stream name. CICS does this either by using a user-defined JOURNALMODEL resource definition (if one exists), or by using default names created by resolving symbolic names.

Mapping of the system log stream

On a cold start, or warm or emergency restart, CICS retrieves the system log stream name from the CICS global catalog.

CICS uses the default log stream names unless you provide a JOURNALMODEL resource definition for the system log.

If there are JOURNALMODEL definitions for your system logs (CICS finds JOURNALMODEL definitions with JOURNALNAME(DFHLOG) and JOURNALNAME(DFHSHUNT)), it attempts to connect to the system log streams named in these definitions. System log stream names must be unique to the CICS region.

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

If there are no suitable JOURNALMODEL definitions, CICS attempts to connect to system log streams, using the following default names:

where ‘userid’ is the RACF® userid under which the CICS address space is running, and ‘applid’ is the region’s VTAM® APPL name. The CSD group DFHLGMOD holds the CICS-supplied JOURNALMODEL definitions for the default DFHLOG and DFHSHUNT log streams.

Before you try to use these default log stream names, ensure that

If these log streams are not available (perhaps they have not been defined to MVS) or the definitions are not found (perhaps they have not been installed), CICS attempts to create system log streams using a model log stream named &sysname.LSN_last_qualifier.MODEL, where:

If you do not provide a JOURNALMODEL resource definition for DFHLOG and DFHSHUNT, or if you use the CICS definitions supplied in group DFHLGMOD, the model names default to &sysname.DFHLOG.MODEL and &sysname.DFHSHUNT.MODEL. Once these log streams have been created, CICS then connects to them.

Figure 9 shows a graphical representation of the system log mapping process during an INITIAL start.

Figure 9. How CICS maps the system log (DFHLOG) to a log stream name (LSN) during an INITIAL start. CICS uses the same process for the secondary system log, DFHSHUNT.
 This diagram shows a graphical representation of the system log mapping process during an INITIAL start as described above.
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