BUFFPOOL settings in WebSphere MQ for z/OS are recovered from checkpoint records, which overrides CSQINP1 definitions

Technote (troubleshooting)


Problem(Abstract)

In WebSphere MQ for z/OS V5.3.1, the buffer pools defined in the CSQINP1 data sets are not retained across subsystem restarts (as documented), but WebSphere MQ V6.0 and above remembers the changes.

Cause

In WebSphere MQ V6 and above, the queue manager records the current buffer pool sizes in checkpoint log records. These are automatically restored on subsequent queue manager restart. This occurs after processing of the CSQINP1 data set.

Resolving the problem

Starting with WebSphere MQ for z/OS V8.0, you can add the REPLACE option to the DEFINE BUFFPOOL command in CSQINP1 to override the value saved in the checkpoint log record.

For all versions:
If you change buffer pools dynamically with the ALTER BUFFPOOL command, you should also update their definitions in the initialization data set CSQINP1. These definitions would be needed in the event of a COLD START.

For V6 and V7:
Use the DISPLAY USAGE command to display the current buffer pools, their sizes, and page set to buffer pool mapping.

Example command sequence:

  1. Update CSQINP1 data set to increase existing BUFFPOOL(3) from 10000 to 10050 buffers. Before the change, DISPLAY USAGE shows...
    CSQP001I CSQ1 Buffer pool 3 has 10000 buffers

  2. After a restart with the change, CSQOUT1 output shows...
    DEFINE BUFFPOOL( 3 ) BUFFERS(10050)
    CSQ9022I CSQ1 CSQPDBUF ' DEFINE BUFFPOOL' NORMAL COMPLETION


    DISPLAY USAGE still shows BUFFPOOL(3) with 10000 buffers even though the
    CSQINP1 command was successful...
    CSQP001I CSQ1 Buffer pool 3 has 10000 buffers

  3. Issue the command ALTER BUFFPOOL(3) BUFFERS(10050) which results in...
    CSQ9022I CSQ1 CSQPALTB ' ALTER BUFFPOOL' NORMAL COMPLETION

    DISPLAY USAGE shows BUFFPOOL(3) with 10050 buffers

  4. Change CSQINP1 to reduce BUFFPOOL(3) from 10050 to 10000 buffers again and recycle the queue manager. DISPLAY USAGE output still shows BUFFPOOL(3) with 10050 buffers.

  5. Change CSQINP1 to add a new buffer pool BUFFPOOL(4) with 1000 buffers and restart the queue manager, CSQOUT1 output shows...
    DEFINE BUFFPOOL( 4 ) BUFFERS(1000)
    CSQ9022I CSQ1 CSQPDBUF ' DEFINE BUFFPOOL' NORMAL COMPLETION


    DISPLAY USAGE shows...
    CSQP001I CSQ1 Buffer pool 4 has 1000 buffers

  6. Delete the DEFINE BUFFPOOL(4) command from CSQINP1 and recycle the queue manager. DISPLAY USAGE still shows...
    CSQP001I CSQ1 Buffer pool 4 has 1000 buffers

    BUFFPOOL(4) can only be removed by the DELETE BUFFPOOL command.

Prior to WMQ 7.1.0, ALTER BUFFPOOL and DELETE BUFFPOOL cannot be issued from CSQINP1 or CSQINP2 as shown in the table Sources from which to run MQSC commands in the WebSphere MQ for z/OS Concepts and Planning Guide. Beginning with WMQ 7.1.0, ALTER BUFFPOOL and DELETE BUFFPOOL can be issued from CSQINP2.


A related problem:
An incorrect number of buffers is reported by DISPLAY USAGE. Following an ALTER BUFFPOOL command, the queue manager may terminate ABENDS6C6 with REASON=00E50705 following an abend 5C6-00D70120 in CSQP3GET. Apply PM62483 (MQ 7.0.1) or PM63040 (MQ 7.1.0).

Product Alias/Synonym

WMQ MQ

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Document information


More support for:

WebSphere MQ
Configuration

Software version:

6.0, 7.0, 7.0.1, 7.1, 8.0

Operating system(s):

z/OS

Reference #:

1233798

Modified date:

2014-09-22

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