Extending files on tape
Tape data files can be extended using the EXTEND parameter on the Create Tape File (CRTTAPF), Change Tape File (CHGTAPF), and Override with Tape File (OVRTAPF) commands. The system does not support extending tape devices that do not support overwrite capability.
When you extend a file, any existing tape data following the specified file on the tape is no longer accessible by the system.
In the following example, a tape contains four files: FILE1, FILE2, FILE3, and FILE4. If FILE2 is extended, FILE3 and FILE4 are no longer accessible.
If you specify EXTEND(*YES *CHECK) on the OVRTAPF command, the expiration date of the file (FILE3) that is following the extension of (FILE2) is checked. The expiration date is checked before the file (FILE2) is extended. However, the expiration dates of any remaining files (FILE4) are not checked, even if EXTEND(*YES *CHECK) is specified. Figure 1. Extending a file
