VMS Help Sys Parameters, IMGREG_PAGES  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    (Alpha only) IMGREG_PAGES is the number of pages to reserve in
    P1 space for images to be installed with shareable address data.
    If IMGREG_PAGES is set to 0, no images are installed with shared
    address data. The default is 10,000 pages.

    For more information, see the INSTALL section in the OpenVMS
    System Management Utilities Reference Manual.