gtpd1m0lDatabase Reference

Record Processing of General Data Sets

The following discusses:

Record Format

When laying out a GDS record, the record format should take into account the following normal TPF procedures:

Processing Macros

A get general data set entry macro (GDSNC) is provided by TPF to allow an application program to retrieve the information necessary to access a specific data set by initializing the appropriate data level or data event control block (DECB) in the ECB. The GDSNC macro must be issued before subsequent find/file macros and returns the file address of the first record.

The parameters provided with the GDSNC macro allow data records to be retrieved in varying sequences within a particular data set. For example, a data set may be accessed by name only regardless of the number of volumes mounted. In addition, any single volume of a data set may be specified for access.

The get general data set record macro (GDSRC) is used to get subsequent record addresses into the ECB data levels or DECBs for use by find and file macro processing. Any number of ECBs may simultaneously address a data set.

Concurrent updating of a data set among loosely coupled TPF images is supported.

See TPF General Macros for more information about the GDSNC and GDSRC macros. See TPF Concepts and Structures and TPF Application Programming for more information about DECBs.