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