Header format
The header describes
the segments in the record and their actual
location within the record. The length and format of each segment
type is fixed. For a description of the segments, see Program interface record format.
Note: For records retrieved with the SELECT request,
the header always has a length that is a multiple of 32, with any
unused header entries set to 00x. For records created for the INSERT
and REPLACE requests, it is not necessary to set the header length
to a multiple of 32, but if you do, you can use direct byte for byte
comparison of input and output records.
The
header consists of one or more header entries, each entry describing
one segment in the data record. Each header entry is 16 bytes and
consists of:
- Segment name (8 characters)
- A character field containing the name of a segment. If this field is blank, this is the last header entry in the header.
- Offset to segment (1 fullword)
- Offset to the start of this segment within the record from the start of the header. If this data area is from a LIST or SELECT request and it is the last header entry (segment name is blanks), this field contains more information about the request. This is further described under the detailed descriptions of the requests later in this chapter.
- Reserved (4 bytes)
- Reserved for use by HCL Workload Automation for Z.
