VMS Help SET, PROCESS, Qualifiers, /SWAPPING  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /SWAPPING (default)
       /NOSWAPPING

    Requires the PSWAPM (process swap) privilege to disable swapping
    for your process.

    Permits the process to be swapped. By default, a process that is
    not currently executing can be removed from physical memory so
    that other processes can execute. If you specify the /NOSWAPPING
    qualifier, the process is not swapped out of the balance set when
    it is in a wait state.