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.