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.