Accessing DSNs or DSCBs in Sequential Order

You can use the CVAFSEQ macro to request the return of information about the data sets:

DSCBs in indexed (data set name) order (either format-1 and format-8 DSCBs or a format-4 DSCB)
One or more DSCBs in physical-sequential order. (If you are unauthorized, you can request only one DSCB.)
The next data set name in the index.

CVAF reads the DSCBs into buffers identified by the BUFLIST keyword. See CVAFSEQ Macro Overview and Specification for additional information about the macro.

Use the buffer list to specify the argument of each DSCB to be read. For indexed access, request 96-byte DSCBs in the buffer list. For physical-sequential access, request 140-byte DSCBs.

If you select indexed order, CVAF returns each format-1, format-4, or format-8 DSCB pointed to by the index. To return only the data set names in the index (not the DSCBs), specify DSNONLY=YES. CVAF updates the DSN area specified in the CVAFSEQ macro with the data set name of each DSCB read, every time you issue CVAFSEQ. CVAF also returns the CCHHR of the DSCB in the argument area supplied with the ARG keyword.

Note: The returned DSCB from CVAFSEQ always includes the key portion of the DSCB when the supplied length is 140 bytes for the buffer (field BFLELTH). The mapping for structure IECSDSF4 in macro IECSDSL1, however, does not include the key portion of the DSCB. Therefore, if you use the format-4 DSCB fields defined in this structure (all fields starting with DS4), you must adjust the starting point of the first field in the IECSDSF4 structure to correspond to 44 bytes into the returned buffer.

For indexed access, a CVAFSEQ request will fail if the EADSCB=OK indicator is not set and the DSCB attempted to be read is a format-8 DSCB. CVAF return code of 4 with a CVAF status code (CVSTAT) of STAT082 will be set.