VSAM Share Options determine how users can access VSAM datasets. By using these options, different users/jobs can be granted different levels of access to a single VSAM dataset. As part of the DEFINE statement, the SHAREOPTS parameter is written as SHAREOPTS (a,b). Here, a represents the cross-region share option, which indicates how two or more users/jobs on the same MVS system can share a file, and b represents the cross-system share option, which indicates how two or more users/jobs on different MVS systems can share a file. In most cases, this value is SHAREOPTS(2 3).
If the cross-region value is 2, multiple users can simultaneously process the file provided that only one of them is an updater. The value 3 for the cross-system indicates the file can be processed by any number of jobs/users (VSAM does not ensure integrity).
