MVS BOOT CAMP: Leveraging Your Coupling Facility to Enhance LOGREC

by John E. Johnston
October 1, 2004

The DEFINE LOGSTREAM statement defines the LOGREC log stream:

•    The name must be SYSPLEX.LOGREC.ALLRECS.
•    STRUCTNAME must match the name specified in the CFRM policy.
•    AUTODELETE(YES) and RETPD(90) parameters work together to automatically delete records more than 90 days old.
•    LS_SIZE specifies the number of 4KB blocks of the DASD data set used to offload the structure when it reaches the HIGHOFFLOAD full percentage.
•    HLQ specifies the High-Level Qualifier of DASD offload data set. This HLQ is placed at the beginning of the log stream name. For example, the offload data sets in this example would be named SAPZPLEX.SYSPLEX. LOGREC.ALLRECS.xxx (where xxx is a counter the MVS logger function adds).

After you run the IXCMIAPU utility, you can check the status of the MVS logger by issuing these commands:

D LOGGER, STATUS
(displays the status of the MVS Logger)
D LOGGER,CONNECTION
(displays active Logger log streams)

Now it’s time to tell LOGREC to change its recording medium from the LOGREC disk data set to our newly defined log stream. To do this, issue this command:

SETLOGRC LOGSTREAM

You should see responses to the command as shown in Figure 6. You can also check the status of the LOGREC recording medium by issuing the “D LOGREC” command.



You can change your IEASYS parmlib member to direct LOGREC to record its data directly to the log stream instead of the disk data set. However, this isn’t recommended. Rather, the recommended method is to let LOGREC come up after an IPL with the standard method of using the disk data set. Then, after the IPL, issue the SETLOGRC command to switch the recording medium to the log stream. The reason for this is that if the LOGREC log stream isn’t available during the IPL, the IPL won’t complete.

Final Thoughts
The JCL you use to generate the EREP report will need to change to read the log stream rather than the DASD LOGREC data set. There’s a sample job for this (and more) in SYS1.SAMPLIB(IFBEREPS).

Using a coupling facility structure and the MVS logger for collecting LOGREC data is a much simpler method to maintain LOGREC data. While you’re revamping LOGREC and EREP, you should also check out the online LOGREC viewer. This handy utility lets you view LOGREC data online via an ISPF application. You can download this free utility from IBM at www-ibm.com/servers/s390/os390/downloads/ logrec_viewer.html.

References
Systems Programmers Guide to z/OS System Logger (SG24-6898-00)
Parallel Sysplex Operational Scenarios (SG24-2079-00)