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Accessing DSNs or DSCBs in Sequential Order z/OS DFSMSdfp Advanced Services SC23-6861-01 |
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You can use the CVAFSEQ macro to request the return of information
about the data sets:
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. |
Copyright IBM Corporation 1990, 2014
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