Defining CICS general logs

Journals on general log streams comprise user journals, forward recovery logs, and autojournals.

Planning log streams for use by your user journals and autojournals

General logs are identified as such by their MVS™ log stream names, which are differentiated from system log streams in that their names do not end with DFHLOG or DFHSHUNT.

Using JOURNALMODELs to define general logs

If you are running multiple cloned copies of your application-owning regions (AORs), it is probable that the logged data is common and that you would want to merge the data from all of the AORs to the same log stream. The following JOURNALMODEL resource definition maps CICS® journals of the same journal identifier to a shared log stream:

  DEFINE GROUP(MERGE) DESC('Merge journals across cloned CICS regions')
         JOURNALMODEL(JRNLS) JOURNALNAME(DFHJ*) TYPE(MVS)
         STREAMNAME(&USERID..SHARED.&JNAME.)

In this example, the literal SHARED is used in place of the default CICS applid, which would require a unique log stream for each region.

You might want to use JOURNALMODELs to map journals to log streams if the CICS region userid changes between runs. This could be the case, for example, where CICS test regions are shared between groups of developers. It would be wasteful to create log streams with a different high level qualifier for each user and you might prefer to use the same log streams regardless of which developer starts up a CICS region. For example, the following generic JOURNALMODEL definition maps all journals not defined by more explicit definitions to the same log stream

  DEFINE GROUP (TEST) DESC('Journals for test CICS regions')
         JOURNALMODEL(JRNLS) JOURNALNAME(*) TYPE(MVS)
         STREAMNAME(TESTCICS.&APPLID..&JNAME.)

You might want to merge data written by CICS regions using different journal names to a single log stream.

  DEFINE GROUP (TEST) DESC('Merging journals 10 to 19')
         JOURNALMODEL(J10TO19) JOURNALNAME(DFHJ1*) TYPE(MVS)
         STREAMNAME(&USERID..MERGED.JNLS)
  DEFINE GROUP (TEST) DESC('Merging journalnames JNLxxxxx')
         JOURNALMODEL(JNLXXXXX) JOURNALNAME(JNL*) TYPE(MVS)
         STREAMNAME(&USERID..MERGED.JNLS)

The last qualifier of the stream name is used as the CICS resource name for dispatcher waits. Therefore, if it is self-explanatory, it can be helpful when interpreting monitoring information and CICS trace entries.

Planning log streams for use by your forward recovery logs

CICS performs the logging for RLS and non-RLS data sets. You can share a forward recovery log stream between multiple data sets - you do not need to define a log stream for each forward-recoverable data set. Your decision is a balance of transaction performance, rapid recovery, and the work involved in managing a large number of log streams.

For a data set open in RLS mode, the MVS logger merges all the forward recovery log records from the various CICS systems on to the shared forward recovery log.

Some points to consider are:

Planning log streams for use by your log of logs (DFHLGLOG)

The log of logs is written by CICS to provide information to forward recovery programs such as CICS VSAM Recovery (CICSVR). The log of logs is a form of user journal containing copies of the tie-up records written to forward recovery logs. Thus it provides a summary of which recoverable VSAM data sets CICS has used, when they were used, and to which log stream the forward recovery log records were written.

If you have a forward recovery product that can utilize the log of logs, you should ensure that all CICS regions sharing the recoverable data sets write to the same log of logs log stream.

  DEFINE GROUP(JRNL) DESC('Merge log of logs')
         JOURNALMODEL(DFHLGLOG) JOURNALNAME(DFHLGLOG) TYPE(MVS)
         STREAMNAME(&USERID..CICSVR.DFHLGLOG)
Note:
Note that this definition is supplied in group DFHLGMOD in DFHLIST.

If you don’t have a forward recovery product that can utilize the log of logs you can use a dummy log stream:

  DEFINE GROUP(JRNL) DESC('Dummy log of logs')
         JOURNALMODEL(DFHLGLOG) JOURNALNAME(DFHLGLOG) TYPE(DUMMY)

Do not share the log of logs between test and production CICS regions, because it could be misused to compromise the contents of production data sets during a restore.

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