alled with options that are incompatible for
JIT execution. A callback function can therefore be used to determine whether a
match operation was executed by JIT or by the interpreter.
</P>
<P>
You may safely use the same JIT stack for more than one pattern (either by
assigning directly or by callback), as long as the patterns are all matched
sequentially in the same thread. In a multithread application, if you do not
specify a JIT stack, or if you assign or pass back NULL from a callback, that
is thread-saf