A volume catalog (VOLCAT) is a catalog that contains only tape library and tape volume entries. A general VOLCAT contains all tape library entries and any tape volume entries that do not point to a specific VOLCAT. A specific VOLCAT cannot contain tape library entries. It contains a specific group of tape volume entries based on the tape volume serial numbers (tape volsers).

Table 1 lists the tape library and tape volume entries and approximates the number of bytes needed to maintain information in the tape volume catalog. The values do not necessarily represent the length of any one record.

Use the following steps to estimate the space allocation for a tape volume catalog:

1. Estimate the number of tape library entries and tape volume entries to be cataloged in the VOLCAT. Use only tape volume entries for a specific VOLCAT because it cannot contain tape library entries.
2. Using these figures, determine the total space requirement, in bytes. This figure is the minimum amount of space that the VOLCAT requires.
3. Divide the total number of bytes by 1024 to determine the number of kilobytes, or by 1048576 to determine the number of megabytes. Round the result up to the nearest whole integer, and specify KILOBYTES or MEGABYTES as appropriate.