Set Log on z/OS®

Use the Set Log (MQCMD_SET_LOG) command to dynamically change certain log system parameter values initially set by your system parameter module at queue manager startup.

    Required parameters:
    ParameterType

    Optional parameters (if the value of ParameterType is MQSYSP_TYPE_SET:
    CommandScope , DeallocateInterval , LogCompression , MaxArchiveLog , MaxConcurrentOffloads , MaxReadTapeUnits , OutputBufferCount

    Optional parameters if ParameterType type is MQSYSP_TYPE_INITIAL:
    CommandScope


Required parameters

    ParameterType (MQCFIN)
    Parameter type (parameter identifier: MQIACF_SYSP_TYPE). Specifies how the parameters are to be set:

      MQSYSP_TYPE_INITIAL
      The initial settings of the log system parameters. This MQSYSP_TYPE_INITIAL resets all the log system parameters to the values at queue manager startup.

      MQSYSP_TYPE_SET
      This MQSYSP_TYPE_SETindicates that you intend to change one, or more, of the archive log system parameter settings.


Optional parameters

    CommandScope (MQCFST)
    Command scope (parameter identifier: MQCACF_COMMAND_SCOPE). Specifies how the command is executed when the queue manager is a member of a queue-sharing group. We can specify one of the following:

    • blank (or omit the parameter altogether). The command is executed on the queue manager on which it was entered.
    • a queue manager name. The command is executed on the queue manager you specify, providing it is active within the queue sharing group. If you specify a queue manager name other than the queue manager on which it was entered, you must be using a queue sharing group environment, and the command server must be enabled.
    • an asterisk (*). The command is executed on the local queue manager and is also passed to every active queue manager in the queue sharing group.

    The maximum length is MQ_QSG_NAME_LENGTH.

    DeallocateInterval (MQCFIN)
    Deallocation interval (parameter identifier: MQIACF_SYSP_DEALLOC_INTERVAL).

    Specifies the length of time, in minutes, that an allocated archive read tape unit is allowed to remain unused before it is deallocated. This parameter, together with the MaxReadTapeUnits parameter, allows IBM MQ to optimize archive log reading from tape devices. You are recommended to specify the maximum values, within system constraints, for both parameters, in order to achieve the optimum performance for reading archive tapes.

    Specify a value in the range zero and 1440. Zero means that a tape unit is deallocated immediately. If you specify a value of 1440, the tape unit is never deallocated.

    LogCompression (MQCFIN)
    Log compression parameter (parameter identifier: MQIACF_LOG_COMPRESS).

    Specifies the log compression algorithm to enable.

    The possible values are:

      MQCOMPRESS_NONE
      Log compression is disabled.

      MQCOMPRESS_RLE
      Enable run-length encoding log compression.

      MQCOMPRESS_ANY
      Enable the queue manager to select the compression algorithm that gives the greatest degree of log record compression.

    For more details see The log files.

    MaxArchiveLog (MQCFIN)
    Specifies the maximum number of archive log volumes that can be recorded in the BSDS (parameter identifier: MQIACF_SYSP_MAX_ARCHIVE).

    When this value is exceeded, recording recommences at the start of the BSDS.

    Specify a value in the range 10 through 100.

    MaxConcurrentOffloads (MQCFIN)
    Specifies the maximum number of concurrent log offload tasks (parameter identifier: MQIACF_SYSP_MAX_CONC_OFFLOADS).

    Specify a decimal number between 1 and 31. If no value is specified the default of 31 applies.

    Configure a number lower than the default if your archive logs are allocated on a tape device, and there are constraints on the number of such devices that can be concurrently allocated to the queue manager.

    MaxReadTapeUnits (MQCFIN)
    Specifies the maximum number of dedicated tape units that can be allocated to read archive log tape volumes (parameter identifier: MQIACF_SYSP_MAX_READ_TAPES).

    This parameter, together with the DeallocateInterval parameter, allows IBM MQ to optimize archive log reading from tape devices.

    Specify a value in the range 1 through 99.

    If you specify a value that is greater than the current specification, the maximum number of tape units allowable for reading archive logs increases. If you specify a value that is less than the current specification, tape units that are not being used are immediately deallocated to adjust to the new value. Active, or premounted, tapes remain allocated.

    OutputBufferCount (MQCFIN)
    Specifies the number of 4 KB output buffers to be filled before they are written to the active log data sets (parameter identifier: MQIACF_SYSP_OUT_BUFFER_COUNT).

    Specify the number of buffers in the range 1 through 256.

    The larger the number of buffers and the less often the write takes place improves the performance of IBM MQ. The buffers might be written before this number is reached if significant events, such as a commit point, occur.