# pcre2_jit_stack_assign man page

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## SYNOPSIS

#include <pcre2.h>

void pcre2_jit_stack_assign(pcre2_match_context *mcontext, pcre2_jit_callback callback_function, void *callback_data);

## DESCRIPTION

This function provides control over the memory used by JIT as a run-time stack when pcre2_match() or pcre2_jit_match() is called with a pattern that has been successfully processed by the JIT compiler. The information that determines which stack is used is put into a match context that is subsequently passed to a matching function. The arguments of this function are:

      mcontext       a pointer to a match context
      callback       a callback function
      callback_data  a JIT stack or a value to be passed to the callback

If mcontext is NULL, the function returns immediately, without doing anything.

If callback is NULL and callback_data is NULL, an internal 32KiB block on the machine stack is used.

If callback is NULL and callback_data is not NULL, callback_data must be a valid JIT stack, the result of calling pcre2_jit_stack_create().

If callback not NULL, it is called with callback_data as an argument at the start of matching, in order to set up a JIT stack. If the result is NULL, the internal 32KiB stack is used; otherwise the return value must be a valid JIT stack, the result of calling pcre2_jit_stack_create().

You may safely use the same JIT stack for multiple patterns, as long as they are all matched in the same thread. In a multithread application, each thread must use its own JIT stack. For more details, see the pcre2jit page.

There is a complete description of the PCRE2 native API in the pcre2api page and a description of the POSIX API in the pcre2posix page.

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