/sys$common/syshlp/helplib.hlb SET, WORKING_SET, Qualifiers, /LIMIT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /LIMIT=n

    Specifies the size to which the working set is to be reduced at
    image exit.

    If you specify a value greater than the current quota, the quota
    value is also increased.