## Runtime Configuration

The behaviour of these functions is affected by settings in php.ini.

PCRE Configuration Options
Name | Default | Changeable | Changelog
--- | --- | --- | ---
pcre.backtrack_limit | "1000000" | PHP_INI_ALL | Available since PHP 5.2.0.
pcre.recursion_limit | "100000" | PHP_INI_ALL | Available since PHP 5.2.0.
pcre.jit | "1" | PHP_INI_ALL | Available since PHP 7.0.0.

For further details and definitions of the PHP_INI_* modes, see the Where a configuration setting may be set.

Here's a short explanation of the configuration directives.

`pcre.backtrack_limit` integer

  PCRE's backtracking limit. Defaults to 100000 for PHP < 5.3.7.

`pcre.recursion_limit` integer

  PCRE's recursion limit. Please note that if you set this value to a high number you may consume all the available process stack and eventually crash PHP (due to reaching the stack size limit imposed by the Operating System).

`pcre.jit` boolean

  Whether PCRE's just-in-time compilation is going to be used.