Having the OMVS command and the shell run in the same (shared) TSO/E address space saves one address space per user and simplifies transaction accounting, as managed by the operating system. The shell shares the address space (SHAREAS) by default, unless the shell is a SETUID or SETGID program and the owning UID or GID is not the same as the current owner.

If you specify NOSHAREAS, the shell might keep running even after the QUIT subcommand was entered; in most cases, it will not.

For more information about shared address space, see Performance: Running executable files.