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

       /EXTENT=quota

    Specifies the maximum size to which the image being executed in
    the process can increase its physical memory size.

    The default quota is that established at system generation time.
    The minimum value required for any process to execute is 10
    pages.

    Specify the value of n as a number of 512-byte pagelets on
    Alpha or 512-byte pages on VAX. Note that the operating system
    rounds up this value to the nearest CPU-specific page so that
    actual amount of physical memory allowed may be larger than the
    specified amount on Alpha.

    The extent quota is nondeductible.