PCRE - Perl-compatible regular expressions
This function is used to create a stack for use by the code compiled by the JIT optimization of pcre[16|32]_study(). The arguments are a starting size for the stack, and a maximum size to which it is allowed to grow. The result can be passed to the JIT run-time code by pcre[16|32]_assign_jit_stack(), or that function can set up a callback for obtaining a stack. A maximum stack size of 512K to 1M should be more than enough for any pattern. For more details, see the pcrejit page.
There is a complete description of the PCRE native API in the pcreapi page and a description of the POSIX API in the pcreposix page.