MMG_CTLFLAGS is a bitmask used to enable or disable memory
    management-related activities.

    The first two bits, 0 and 1, control the proactive memory
    reclamation mechanisms. Bit 2 controls deferred memory testing.

    The following bit mask values are defined:

    Bit    Description

    0      If this bit is set, reclamation is enabled by trimming
           from periodically executing, but otherwise idle,
           processes. This occurs when the size of the free list
           plus the modified list drops below two times the value of
           FREEGOAL. This function is disabled if the bit is clear.

    1      If this bit is set, reclamation is enabled by outswapping
           processes that have been idle for longer than LONGWAIT
           seconds. This occurs when the size of the free list drops
           below FREEGOAL. This function is disabled if the bit is
           clear.

    2      Controls deferred memory testing (only on AlphaServer
           4100 systems). You can use this bit to speed up elapsed
           bootstrap time by controlling when memory is tested:

           o  If the bit is clear (the default), OpenVMS tests memory
              as a background activity, which might or might not
              complete before the end of the bootstrap process.

           o  If the bit is set, all memory is tested in the
              bootstrap process by the end of the EXEC_INIT phase
              (that is, before IPL is lowered from 31).

    3      Reserved to OpenVMS use; must be zero.

    4      If this bit is clear (the default), all page sizes
           supported by hardware can be used to map resident memory
           sections on Integrity servers. If this bit is set, page
           sizes on Integrity servers are limited to the maximum
           GH factor available on Alpha systems (512 * <system page
           size>).

    5-7    Reserved for future use.

    MMG_CTLFLAGS is an AUTOGEN and DYNAMIC parameter.