You are viewing the version of this documentation from Perl 5.31.2. This is a development release of Perl.
${^RE_COMPILE_RECURSION_LIMIT}

The current value giving the maximum number of open but unclosed parenthetical groups there may be at any point during a regular expression compilation. The default is currently 1000 nested groups. You may adjust it depending on your needs and the amount of memory available.

This variable was added in Perl v5.30.0.