If however you want to position the current volume according to the option specified in the DISP parameter of the DD statement, you code DISP in the OPEN macro.

DISP specifies that a tape volume is to be disposed of in the manner implied by the DD statement associated with the data set. Direct access volume positioning and disposition are not affected by this parameter of the OPEN macro. There are several dispositions that can be specified in the DISP parameter of the DD statement; DISP can be PASS, DELETE, KEEP, CATLG, or UNCATLG.

The resultant action when an end-of-volume condition arises depends on (1) how many tape units are allocated to the data set, and (2) how many volumes are specified for the data set in the DD statement. The UNIT and VOLUME parameters of the DD statement associated with the data set determine the number of tape units allocated and the number of volumes specified. If the number of volumes is greater than the number of units allocated, the current volume will be rewound and unloaded. If the number of volumes is less than or equal to the number of units, the current volume is merely rewound.

For magnetic tape volumes that are not being unloaded, positioning varies according to the direction of the last input operation and the existence of tape labels. When a JCL disposition of PASS or RETAIN is specified, the result is the same as the OPEN or CLOSE LEAVE option. The CLOSE disposition option takes precedence over the OPEN option and the OPEN and CLOSE disposition options take precedence over the JCL.