PCRE2 - Perl-compatible regular expressions (revised API) .rs #include <pcre2.h>

 int pcre2_set_max_pattern_length(pcre2_compile_context *ccontext,  " PCRE2_SIZE value);" 

. .rs This function sets, in a compile context, the maximum text length (in code units) of the pattern that can be compiled. The result is always zero. If a longer pattern is passed to pcre2_compile() there is an immediate error return. The default is effectively unlimited, being the largest value a PCRE2_SIZE variable can hold.

There is a complete description of the PCRE2 native API in the HREF
pcre2api
page and a description of the POSIX API in the HREF
pcre2posix
page.