Defining a Logrec Log Stream

First of all and before defining a Logrec log stream, the Systems Programmer should make sure that the system in question was IPLed with a Logrec data set initialized by IFCDIP00. If this is not the case, you cannot change the Logrec recording medium from LOGSTREAM to DATASET using the SETLOGRC command and therefore you’ll have to IPL the system in order to be able to use the Logrec log stream you’ve defined.

To use the Logrec log stream, the Systems Programmer must first set up the system to use system logger functions. IBM recommends that you use a coupling facility log stream for LOGREC so that you can merge data from multiple systems in a sysplex.

On a single system sysplex (monoplex) the system can also use a DASD only log stream (which is single system in scope). However, this is not recommended for a multi-system sysplex because since we can only have one Logrec log stream per sysplex, this would mean that if using a DASD only Logrec log stream, only one system of the sysplex would be able to access it. Therefore for a multi-system sysplex it is advisable to use a LOGSTREAM Logrec log stream.

JCL:

// IXCMIAPU JOB CLASS=A,MSGLEVEL=(1,1),MSGCLASS=X,NOTIFY=&SYSUID
//DEFINE   EXEC PGM=IXCMIAPU
//SYSPRINT DD   SYSOUT=A
//SYSIN    DD   *
DATA TYPE (LOGR)
DEFINE STRUCTURE NAME(LOGRECSTRUCTURE)
LOGSNUM(1)
AVGBUFSIZE(4068)
MAXBUFSIZE(4068)
DEFINE LOGSTREAM NAME(SYS1.SYSPLEX.LOGREC)
STRUCTNAME(LOGRECSTRUCTURE)
/*

MAXBUFSIZE must be at least 4068 because logrec writes records in one page blocks. Specify SMS storage group, storage, data and management classes such that when one data set is full, another is allocated. Allocate as much space as is allocated for all the logrec data sets on the systems in the sysplex before migrating to a Logrec log stream.

To start using the Logrec log stream either specify LOGREC=LOGSTREAM in the IEASYSxx parmlib member or, after IPLing with LOGREC=dsname, use the SETLOGRC command to change the Logrec recording medium to a Logrec log stream. Bear in mind though that if you IPL the system with LOGREC=LOGSTREAM, you cannot use the SETLOGRC command to change the Logrec recording medium to a Logrec data set.

Important!

 

Now you have the Logrec log streams defined and ready, and you have even set up the system to start using them. Are you done with your tasks? The answer is no! You still need to update the EREP jobs that your system uses to start using the Logrec log stream. To do this the Systems Programmer will have to go through the JCL and:

• Change the SERLOG DD DSN=SYS1.LOGREC statement associated with a Logrec data set to an ACCIN DD DSN=SYS1.SYSPLEX.LOGREC statement, with corresponding SUBSYS parameters, to associate EREP with the logrec log stream.
• Identify the input as a history data set. Leave the output to a history data set as currently recommended, because all subsequent steps should already use the history data set as input. (Note: using a Logrec log stream as input for multiple steps is not recommended because each subsequent step processes more records than the prior, causing numbers and data in successive reports not to match).
• Subsequent EREP report steps that normally process history data sets no longer need to concatenate one history data set per system.