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Specifies the maximum length of a block for auxiliary trace data sets.

By default, C\Prof will create auxiliary trace data sets with a data block size of 4096 bytes. This is useful when using the CICS trace utility print program as it requires a block size of 4096. If you do not plan to use the CICS trace utility print program, you can improve the performance of C\Prof by adding BLKSIZE=24576 to the collector configuration file. The larger block size is fully supported by all C\Prof services and reduces the amount of I/O required to perform the operation.

The BLKSIZE must be a multiple of 4096. C\Prof rounds the specified BLKSIZE down to the nearest multiple of 4096, for example if you specify BLKSIZE=27998 for half-track blocking then BLKSIZE=24576 is used.

The maximum value of BLKSIZE is 32768, however use of this value is not recommended as the resultant auxiliary trace data set will be almost twice as large as necessary due to half of every track being wasted.

BLKSIZE may also be specified on the AUXILIARY control statement. For more information, see BLKSIZE=value.