Using model log streams

To avoid defining explicitly each log stream used by each of your CICS® regions, you can use model log stream definitions.

Using models, log streams are defined to MVS™ dynamically, on their first usage. Figure 1 shows an example of coupling facility model definitions for CICS primary and secondary system log streams.

Figure 1. Example model definitions for coupling facility system log streams. The value sysname is the sysid of the MVS image in which the CICS region or regions are running.

//DEFLOGS  JOB ...
//LOGDEFN  EXEC PGM=IXCMIAPU
//STEPLIB  DD DSN=SYS1.MIGLIB,DISP=SHR
//SYSPRINT DD SYSOUT=*
//******************************************************************
//*                                                                *
//* Define coupling facility model log streams for CICS system log.*
//*                                                                *
//* The LOWOFFLOAD value is for illustration only --               *
//* substitute a value appropriate for your environment.           *
//*                                                                *
//******************************************************************
//SYSIN    DD *
  DATA TYPE(LOGR) REPORT(NO)
  DEFINE LOGSTREAM NAME(sysname.DFHLOG.MODEL)
                   MODEL(YES)
                   STRUCTNAME(LOG_DFHLOG_001)
                   LOWOFFLOAD(40) HIGHOFFLOAD(80)
                   STG_DUPLEX(YES) DUPLEXMODE(COND)
  DEFINE LOGSTREAM NAME(sysname.DFHSHUNT.MODEL)
                   MODEL(YES)
                   STRUCTNAME(LOG_DFHSHUNT_001)
                   LOWOFFLOAD(40) HIGHOFFLOAD(80)
                   STG_DUPLEX(YES) DUPLEXMODE(COND)

For detailed information about using model log streams, see Model log streams for CICS general logs. For information about the mapping of CICS journal definitions to log stream names, see Mapping of general log streams.

When using model log streams, note these points:

For coupling facility log streams, a model log stream definition determines the coupling facility structure in which the new log streams are created. On an MVS image that runs both CICS production and CICS test regions, take care that the system logs for the production regions are kept separate from the system logs for the test regions.
You must take into account recovery when using model log streams to define CICS system logs. See Recovery considerations for more information.