OPS/REXX Built-in Functions › OPSVSAM Function › Access Strategies

Access Strategies

The following are the access strategies for each type of VSAM file:

KSDS

A key sequenced data set may be accessed sequentially without a key argument, or it may be accessed directly by specifying a full or partial key. To avoid a record not found condition-unless the KGE search type is specified-any partial keys that you specify for point and read functions must match a real key up to the length specified.

The key argument for OPSVSAM is a string value. The key length may be specified when a substring or a blank padded extension of the string is desired. The default key length is the length of the key argument string.

RRDS

A relative record data set may be accessed sequentially without a key argument, or it may be accessed directly by specifying the relative record number of the desired record. Record inserts must indicate the new relative record number. You may specify the key argument for OPSVSAM as a REXX numeric string or a four-byte binary value (for example, '0000001'x).

ESDS

An entry-sequenced data set may be accessed sequentially without a key argument, or it may be accessed directly by specifying the relative byte address of the desired record. Record inserts are always placed at the end of a data set. You may specify the key argument for OPSVSAM as a four-byte RBA binary value only (for example, '000001A0'x).