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

       /SYSTEM[=base-address]

    Directs the linker to create a system image and optionally allows
    you to specify the address at which the image should be loaded
    into memory. A system image cannot be activated with the RUN
    command; it must be bootstrapped or otherwise loaded into memory.

    The base-address specifies the address at which the image is to
    be loaded in virtual memory. You can specify a base address in
    hexadecimal (%X), octal (%O), or decimal (%D) format. The default
    base address is %X80000000.

    Note that if you specify the /HEADER qualifier, the linker
    adjusts the base address to the next highest page boundary if it
    is not already a page boundary. The next highest page boundary is
    the smallest number that is greater than the value specified in
    the base-address parameter and that is divisible by the default
    page size (which is architecture-specific) or the page size
    specified using the /BPAGE qualifier.