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COMM CLRnnn (Reset Alternate Output Data Sets)

Last update March 13, 2019

In z/OS, when running MUF with a SYSOUT MUF startup option specified, you can use CLRML, CLRCBS, CLRSQL, CLRDD, and CLRDST (DBUTLTY COMM functions or console commands) to reset a PXXML, PXXCBS, PXXSQL, PXXDD, or PXXDST data set that has become full during processing.

Note: If you do not want diagnostic and tracing information routed to the Statistics and Diagnostics Area (PXX), you can use the SYSOUT MUF startup option to specify alternate output processing. The SYSOUT parameters define output for Master List snaps, CBS traces, SQL traces, CA Datacom®/DB CA Datacom® Datadictionary™ traces, and DST traces. See Administrating for details.

In response to a CLRML, CLRCBS, CLRSQL, CLRDD, or CLRDST, the specified SYSOUT data set is reset, that is, closed, deallocated, and reallocated (in processing the reset function, the current PXX data set is deallocated and assigned to the class specified in the SYSOUT MUF startup option). Each of the five can generate a report.

The following topics are discussed on this page:

When to Use

Use the COMM CLRnnn option when your Statistics and Diagnostics Area is nearing capacity and you want to clear it out.

How to Use the Console Command

The MUF must be active when you execute this command.

Use the following in your command to initiate this function from the system console. Consult your site operating system documentation for additional syntax information.

►►─┬────────┬─┬─ CLRCBS ─┬────────────────────────────────────────────────────►◄
   └─ COMM ─┘ ├─ CLRDD ──┤
              ├─ CLRDST ─┤
              ├─ CLRML ──┤
              └─ CLRSQL ─┘


  • COMM
    You can omit the COMM function name when submitting this console command.

Required Keywords

  • CLRnnn
    Requests that the specified alternate data set be reset.

How to Use the DBUTLTY Command

The MUF must be active when you execute this command. Execute DBUTLTY with the command:

►►─ COMM OPTION= ─┬─ CLRCBS ─┬─┬──────────────────────┬───────────────────────►◄
                  ├─ CLRDD ──┤ └─ ,IGN68= ─┬─ NO ◄ ─┬─┘
                  ├─ CLRDST ─┤             └─ YES ──┘
                  ├─ CLRML ──┤
                  └─ CLRSQL ─┘


  • COMM
    Invokes the function to pass communication to the MUF.

Required Keyword

    Requests that the specified alternate data set be reset.

Optional Keyword

  • IGN68=
    Specify IGN68=YES to ignore a return code 68. IGN68= is allowed for every ACCESS and COMM function. By ignoring return code 68, you can set up and run JCL that incorporates a stack of DBUTLTY functions without requiring that the MUF be enabled. IGN68= would therefore be useful, for example, if you wanted to load a database without first enabling the MUF, perhaps to allow restart to properly occur. Following is an example showing a stack of DBUTLTY functions that use IGN68=.

     INIT   AREA=A01,DBID=997

    Note: If the CXX is externally secured, the INIT and LOAD functions do not execute without the MUF being available, and IGN68=YES is therefore not recommended.

    A function or functions specified with IGN68=YES generates message DB13001E to note that the function did not occur. Because no error was recognized, however, other functions in the stack continue to execute, and the DBUTLTY step ends without a recognizable error. Message DB13001E signals that the MUF was not enabled.

    The DBSYSID macro parameter DELAY68= can be used to specify the number of minutes that the MUF connection can wait if the MUF is not currently available. But if IGN68=YES is specified, DELAY68= is ignored and the function continues. If the delay is desired, however, either do not specify IGN68=, in which case it defaults to NO, or specify IGN68=NO.

    • Valid Entries:
      NO or YES
    • Default Value:

Example JCL

The following shows the command to reset the PXXML alternate data set.

Note: Use the following as a guide to prepare your JCL. The JCL statements are for example only. Lowercase letters in a statement indicate a value you must supply. Code all statements to your site and installation standards.

 //jobname    See the previous note and JCL Requirements.
 //STEPLIB    See the previous note and JCL Requirements.
//SYSIN    DD *                                   Command input

Sample Report

Following is a sample report page. For an example report header, see Sample Report Headers.

Sample Report COMM CLRML 

                    CONTROL CARD(S)
                    COMM OPTION=CLRML

This page of the report shows the following:

  • The command exactly as entered.
  • An analysis of keywords encountered and expected. Any errors found are flagged with a note in the left margin.
  • Any messages related to syntax processing.


This page of the report shows a message indicating that DBUTLTY successfully placed the request on the MUF communication queue.

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