Processing Different File Types › Generation Data Groups › Batch Interface

Batch Interface

The local file in a file transfer can be specified with the SYSIN01 LFILE parameter or the LCLDS01 DD statement (see the chapter “The Batch Interface”). For TYPE=SCHEDULE (that is, queued) transfers, Generation Data Groups are handled differently depending on the option used.

If the local file is specified with LCLDS01, CA XCOM Data Transport transfers the designated file when the request is made. This is done regardless of whether a generation data set is specified by its relative generation number or its GxxxxV00 suffix.

If the local file is specified as LFILE, it is transferred according to its relative generation number. This permits maximum flexibility without alteration of the production JCL.

If the LCLDS01 DD is used to create a +1 GDG version for TYPE=SCHEDULE transfer, there are additional potential problems:

• When the z/OS JCL performs the allocation of the LCLDS01 DD, it allocates and potentially catalogs the new version, depending on the value of the DISP parameter in the JCL. This new version does not have an end-of-file mark, because it has not yet been opened and closed by a program.
• When the transfer begins on the CA XCOM Data Transport started task, it allocates a new +1 version of the GDG. In cases where the transfer is successful, this results in the creation of two new generations of the GDG. The first version contains garbage, because it was allocated by the z/OS JCL processor and was never opened or closed by a program to write an end-of-file mark. If the transfer fails, under certain conditions the version allocated by the CA XCOM Data Transport started task may be deleted. This leaves the version of the GDG allocated by the z/OS JCL processor as the current version.

All of these potential problems can be avoided if the LOCAL FILE name is specified on the LFILE SYSIN01 parameter, rather than with the LCLDS01 DD statement for TYPE=SCHEDULE transfers.

Note: This distinction is irrelevant to TYPE=EXECUTE transfers because there is no time lag with these types of transfers.