To set user and group IDs in a program

These controls allow users to run a program with the user ID of the file owner or the group ID of the file owner of the program file. They control access authorization a particular program is running. The file owner can set the controls any time, not just in the DD statement.

Do not specify these controls in JCL, because they will be reset when the file is written.

The system overrides the SISUID and SISGID parameters and sets the controls so that no users can run the program when either:

The DD statement creates the file
A user writes in the file, thus changing the program

Then, for the program to be run, the file owner must reset the controls.

SISUID: Specifies that the system set the user ID of the process to be the same as the user ID of the file owner when the file is run as a program.
SISGID: Specifies that the system set the group ID of the process to be the same as the group ID of the file owner when the file is run as a program. The group ID is taken from the directory in which the file resides.