/REENTRANCY
       /REENTRANCY=option
       /REENTRANCY=TOLERANT (D)

    Controls the type of reentrancy that reentrant HP C RTL routines
    exhibit. (See also the DECC$SET_REENTRANCY RTL routine.)

    This qualifier is for use only with a module containing the main
    routine.

    The reentrancy level is set at run time according to the
    /REENTRANCY qualifier specified while compiling the module
    containing the main routine. This option affects the behavior
    of the C RTL, but has no effect on the C++ libraries.

    You can specify one of the following options:

    Option     Usage

    AST        Uses the __TESTBITSSI built-in function to perform
               simple locking around critical sections of RTL code,
               and may additionally disable asynchronous system traps
               (ASTs) in locked region of codes. This type of locking
               should be used when AST code contains calls to DEC C
               RTL I/O routines.
    MULTITHREADDesigned to be used in conjunction with the DECthreads
               product. It performs DECthreads locking and never
               disables ASTs.
    NONE       Gives optimal performance in the RTL, but does
               absolutely no locking around critical sections of
               RTL code. It should be used only in a single threaded
               environment when there is no chance that the thread of
               execution will be interrupted by an AST that would call
               the HP C RTL.
    TOLERANT   Uses the __TESTBITSSI built-in function to perform
               simple locking around critical sections of RTL code,
               but ASTs are not disabled. This type of locking should
               be used when ASTs are used and must be delivered
               immediately. This is the default reentrancy type.