Saves or restores the process image rights for the current
    protected subsystem.
    Format
      SYS$SUBSYSTEM  enbflg
    C Prototype
      int sys$subsystem  (unsigned int enbflg);
1 – Argument
 enbflg
    OpenVMS usage:boolean
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Value specifying whether the protected subsystem identifiers are
    to be saved or restored. If the enbflg argument is set to 0, the
    active subsystem is saved. If it is set to 1, the subsystem is
    restored.