Advanced Topics › Control and Checkpoint File Considerations › How You Allocate Control and Checkpoint Files › Allocate DASD Control Files

Allocate DASD Control Files

Allocate the DASD control file by customizing the sample JCL in the ALLOCCF member of the CAI.CBTDJCL data set. Do not use any other method to allocate CA MIM control files.

Keep the following in mind when allocating DASD control files:

• Allocate control files as contiguous cylinders and on cylinder boundaries.
• The primary control file should be a minimum of 10 cylinders in size.
• Allocate at least one alternate control file to be used as a backup in case the primary control file becomes unusable. You may allocate up to 99 alternate control files.
• Allocate alternate control files to a size slightly larger than the primary control file.
• Do not place alternate control files on the same device as the primary control file.
• If possible, allocate the file in a location that requires minimal or no head movement.

To allocate a DASD control file

1. Issue the following command to determine the next available control file number:

   DISPLAY FILES 
   

2. Create a new control file by customizing the sample JCL in the ALLOCCF member of the CAI.CBTDJCL data set.
3. Issue the following command on all systems in the MIMplex:

   ALLOCATE DSNAME=newdsn,DDNAME=MIMTBLnn
   

   nn

   Specifies the number of the new control file.

4. To verify that the new file was added to the control file list, reissue the following command:

   DISPLAY FILES