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Changing the Block Size for the Control Files

CA MIM dynamically adjusts the block size that is used to access its control files. For a DASD file that has already been formatted, MIM gets the block size from the file itself. For a DASD file that must be formatted, CA MIM determines an optimal block sized based on the device type and the size of the file. The actual block size is never less than the value specified through MIMINIT BLKSIZE=, nor greater than 32760.

To change the minimum block size, specify a new value for the BLKSIZE parameter on a MIMINIT statement. For example, you can change the block size to 12288 bytes by specifying this MIMINIT statement in the INIT MIM file:

MIMINIT BLKSIZE=12288

To see the actual block size for the active control file, you can issue the ‘DISPLAY MIM IO’ command.

Note: In some environments, larger BLKSIZE values can improve system performance by reducing the number of discrete read/write operations to the CA MIM control file. This especially is true, when message traffic is extremely heavy for the CA MIC component of CA MIM.