The common VTOC access facility (CVAF) macros and tasks discussed in this section consist of the following:

• CVAFDIR directly accesses one or more DSCBs.
• CVAFDSM obtains volume free space information.
• CVAFFILT reads sets of DSCBs for one or more DASD data sets.
• CVAFSEQ retrieves the following:
  • Data set names from an active VTOC index
  • DSCBs in physical-sequential order
  • DSCBs in data set name order (index required).
• CVAFTST determines if a DASD volume has an active VTOC index.

Coding CVAF VTOC Access Macros, contains descriptions of these macros and examples of their use.

When calling CVAF, your program can be in either 24-bit or 31-bit addressing mode. If it is in 31-bit mode, the control blocks shown in Figure 1 might reside above the 16 MB line. All these areas must be accessible in your program's storage key.