Defining coupling facility log streams

Use the MVS™ IXCMIAPU utility to define coupling facility log streams to the LOGR couple data set.

The following code sample shows the basic syntax to define a coupling facility log stream:

DEFINE LOGSTREAM NAME(log_stream_name)
             STRUCTNAME(structure_name)
             LOWOFFLOAD(low_offload) HIGHOFFLOAD(high_offload)
             STG_DUPLEX(YES|NO) DUPLEXMODE(COND|UNCOND)

For detailed information about the full range of log stream attributes, see the z/OS MVS Setting Up a Sysplex manual.

Figure 1 shows example definitions for a pair of coupling facility log streams associated with a CICS® system log. The definitions are for the CICS primary and secondary system log streams. The region_userid value is the RACF® user ID under which the CICS address space is running. The applid value is the z/OS® Communications Server APPL name of the CICS region (taken from the APPLID system initialization parameter).

The primary and secondary log streams are placed in different structures because of the large disparity in data volumes written to the primary and secondary system logs.

Figure 1. Example definitions of coupling facility log streams.

//DEFLOGS  JOB ...
//LOGDEFN  EXEC PGM=IXCMIAPU
//STEPLIB  DD DSN=SYS1.MIGLIB,DISP=SHR
//SYSPRINT DD SYSOUT=*
//******************************************************************
//*                                                                *
//* Define coupling facility 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(region_userid.applid.DFHLOG)
                   STRUCTNAME(LOG_DFHLOG_001)
                   LOWOFFLOAD(40) HIGHOFFLOAD(80)
                   STG_DUPLEX(YES) DUPLEXMODE(COND)
  DEFINE LOGSTREAM NAME(region_userid.applid.DFHSHUNT)
                   STRUCTNAME(LOG_DFHSHUNT_001)
                   LOWOFFLOAD(40) HIGHOFFLOAD(80)
                   STG_DUPLEX(YES) DUPLEXMODE(COND)