Library /sys$common/syshlp/sysgen.hlb INSTALL, Parameter  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 file-spec

    Specifies the name of a file that is to be installed as a page
    or swap file. This file can reside on any volume that is mounted
    /SYSTEM. The file should be contiguous for best performance.