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Parameter block

 

For a full description of these parameters, see the WebSphere MQ for z/OS System Setup Guide.

Parameter block is any one or more of the following parameters that you want to change:

DEALLCT

Specifies the length of time that an allocated archive read tape unit is allowed to remain unused before it is deallocated. You are recommended to specify the maximum possible values, within system constraints, for both options to achieve the optimum performance for reading archive tapes.

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

The possible values are:

integer

Specifies the maximum time in minutes, between zero and 1439. Zero means that a tape unit is deallocated immediately.

NOLIMIT or 1440

Indicates that the tape unit is never deallocated.

MAXARCH

Specifies the maximum number of archive log volumes that can be recorded in the BSDS. When this number is exceeded, recording begins again at the start of the BSDS.

Use a decimal number in the range 10 through 1000.

MAXRTU(integer)

Specifies the maximum number of dedicated tape units that can be allocated to read archive log tape volumes. This overrides the value for MAXRTU set by CSQ6LOGP in the archive system parameters.

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

  1. The integer value can range from 1 to 99.

  2. If the number specified is greater than the current specification, the maximum number of tape units allowable for reading archive logs increases.

  3. If the number specified 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, tape units remain allocated.

  4. A tape unit is a candidate for deallocation because of a lowered value only if there is no activity for the unit.

  5. When you are asked to mount an archive tape and you reply “CANCEL”, the MAXRTU value is reset to the current number of tape units.

    For example, if the current value is 10, but you reply “CANCEL” to the request for the seventh tape unit, the value is reset to six.

WRTHRSH

Specifies the number of 4 KB output buffers to be filled before they are written to the active log data sets.

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

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

 

Parent topic:

Parameter descriptions


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