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

    SYSTEM_CHECK investigates intermittent system failures by
    enabling a number of run-time consistency checks on system
    operation and recording some trace information.

    Enabling SYSTEM_CHECK causes the system to behave as if the
    following system parameter values are set (although the values
    of the following parameters are not actually changed):

    Parameter        Value       Description

    BUGCHECKFATAL    1           Crash the system on nonfatal
                                 bugchecks.

    POOLCHECK        %X616400FF  Enable all poolchecking, with an
                                 allocated pool pattern of %x61616161
                                 ('aaaa') and deallocated pool
                                 pattern of x64646464 ('dddd').

    MULTIPROCESSING  2           Enable full synchronization
                                 checking.

    While SYSTEM_CHECK is enabled, the previous settings of the
    BUGCHECKFATAL and MULTIPROCESSING parameters are ignored.
    However, setting the parameter POOLCHECK to a nonzero value
    overrides the setting imposed by SYSTEM_CHECK.

    Setting SYSTEM_CHECK creates certain image files that are capable
    of the additional system monitoring. These image files are
    located in SYS$LOADABLE_IMAGES and can be identified by the
    suffix _MON.

    For information about the type of data checking performed by
    SYSTEM_CHECK, see the description of the ACP_DATACHECK parameter.
    For information about the performance implications of enabling
    SYSTEM_CHECK, see OpenVMS Performance Management.

    On VAX systems, SYSTEM_CHECK is a special parameter, which is
    subject to change at any time and should be modified only if
    recommended by Compaq.