Using a SEQUENTIAL file to access an ESDS

You can open a SEQUENTIAL file that is used to access an ESDS with either the INPUT or the UPDATE attribute. If you use either of the options KEY or KEYTO, the file must also have the KEYED attribute.

Sequential access is in the order that the records were originally loaded into the data set. You can use the KEYTO option on the READ statements to recover the RBAs of the records that are read. If you use the KEY option, the record that is recovered is the one with the RBA you specify. Subsequent sequential access continues from the new position in the data set.

For an UPDATE file, the WRITE statement adds a new record at the end of the data set. With a REWRITE statement, the record rewritten is the one with the specified RBA if you use the KEY option; otherwise, it is the record accessed on the previous READ. You must not attempt to change the length of the record that is being replaced with a REWRITE statement.

The DELETE statement is not allowed for entry-sequenced data sets.