/sys$common/syshlp/helplib.hlb System Services, $SETUP AVOID PREEMPT, Arguments  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 enable

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Enables or disables preemption avoidance. If the enable argument
    is set to 1, preemption avoidance is enabled; if 0, preemption
    avoidance is disabled.