Rational Developer for System z
Enterprise PL/I for z/OS, Version 3.8, Language Reference Manual

SEQUENTIAL and DIRECT attributes

The SEQUENTIAL and DIRECT access attributes apply only to RECORD files, and specify how the records in the file are accessed.

Read syntax diagramSkip visual syntax diagram   .-SEQUENTIAL-.
>>-+-+--------+-+----------------------------------------------><
     '-DIRECT-'
 

Abbreviation: SEQL for SEQUENTIAL

Default: SEQUENTIAL

The DIRECT attribute specifies that records in a data set are directly accessed. The location of the record in the data set is determined by a character-string key. Therefore, the DIRECT attribute implies the KEYED attribute. The associated data set must be on a direct-access storage device.

The SEQUENTIAL attribute specifies that records in a consecutive or relative data set are accessed in physical sequence, and that records in an indexed data set are accessed in key sequence order. For certain data set organizations, a file with the SEQUENTIAL attribute can also be used for direct access or for a mixture of random and sequential access. In this case, the file must have the additive attribute KEYED. Existing records of a data set in a SEQUENTIAL UPDATE file can be modified, ignored, or, if the data set is indexed, deleted.


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