ACCESS: Read or Write a DSCB or VIRs, or Release Buffer Lists

When ACCESS is READ or WRITE, a single DSCB is accessed for an indexed or nonindexed VTOC, or one or more VIRs are accessed for an indexed VTOC.

ACCESS=READ

Specifies that a single DSCB or one or more VIRs are to be read into a buffer whose address is in a buffer list.

If the buffer list is for a DSCB, only one entry is used in the buffer list. The first entry with the skip bit set to zero and a nonzero buffer address is used.

All VIRs whose buffer list entry has the skip bit off are read into a buffer.

DSN and BUFLIST are required if ACCESS=READ for a DSCB buffer list.

ACCESS=WRITE

Specifies that a single DSCB or one or more VIRs are to be written from buffers whose address is in a buffer list.

ACCESS=WRITE is permitted with BRANCH=NO only if the caller is authorized by APF.

DSN and BUFLIST are required if ACCESS=WRITE for a DSCB buffer list.

If any buffer list entry has its modified bit set, only those entries with the modified bit set are written. If no modify bits are on, all VIRs are written.

ACCESS=RLSE

Applies only to VIR buffer lists. It requests the release of one or more buffers in the VIR buffer list chain identified in the BUFLIST keyword, and the release of each buffer list for which all buffers are released.

DSN and BUFLIST are not required if ACCESS=RLSE.

Only buffers in the buffer list with the skip bit set to zero and with a nonzero buffer address are released. The buffer list is not released if any entry has the skip bit set to one.

For an indexed VTOC, if ACCESS=RLSE is coded, buffer lists and buffers pointed to by the BUFLIST keyword are released, along with buffer lists supplied in the CVAF parameter list CVMRCDS and CVIRCDS fields. If the CVMRCDS or the CVIRCDS buffers are supplied in the BUFLIST field, either directly or indirectly through chaining, the keyword MAPRCDS=YES, IXRCDS=KEEP, or MAPRCDS=(NO,0), IXRCDS=(NOKEEP,0) must be coded to prevent CVAF from freeing the buffers more than once. If buffers are released, the CVAF parameter list field pointing to the buffer list is updated.