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Checkpoint Data Set Size Calculation

You can calculate the number of cylinders required for CA Spool checkpoint data set.

To calculate the number of cylinders required for checkpoint data set

  1. Calculate the length of the master track-allocation map:

    Number of spool volumes * 20 + total number of spool tracks allocated (rounded up to a multiple of 4) + 8.

  2. Calculate the number of 4 KB blocks required to hold the master allocation map (round up if necessary):

    Divide the result from Step 1 with 4096.

  3. Calculate number of checkpoint data set tracks required to hold the 4 KB blocks. Round this up to a whole number of cylinders:

    Divide the result from Step 2 with 12.

  4. Calculate the length of the file queue:

    NUMFQES * (256 + PGNLEN) + 32

  5. Calculate the number of 4 KB blocks required to hold the file queue:

    Divide the result from Step 4 with 4096.

  6. Calculate the number of checkpoint data set tracks required to hold these 4 KB blocks. Round this up to a whole number of cylinders.

    Divide the result from Step 5 with 12.

  7. Calculate the total number of checkpoint cylinders required, as the number of cylinders for the allocation map (result from step 3), plus the number of cylinders for the file queue (result from step 6), plus one cylinder.

Note: A whole number of cylinders must be allocated on a cylinder boundary.

Example

The checkpoint data set is allocated on a 3390 disk. Each 3390 disk track holds up to twelve 4 KB data blocks. The number of tracks in the spool dataset is 6000. The default programmer's name length (PGNLEN) is 16. NUMFQES is 3000.

  1. 20+6000+8=6028
  2. 6028/4096=>2 4 KB data blocks
  3. 2/12 => 1 checkpoint track required for the master allocation map. Rounded up to 1 cylinder.
  4. 3000*(256+16)+32 = 816032
  5. 816032/4096=> 200 4 KB data blocks
  6. 200/12=17 =>17 checkpoint tracks required for the file queue. Rounded up to 2 cylinders.
  7. 1+2+1=4 checkpoint cylinders required on a 3390 disk.