pcre2_maketables man page
PCRE2 — Perl-compatible regular expressions (revised API)
const unsigned char *pcre2_maketables(pcre2_general_context *gcontext);
This function builds a set of character tables for character code points that are less than 256. These can be passed to pcre2_compile() in a compile context in order to override the internal, built-in tables (which were either defaulted or made by pcre2_maketables() when PCRE2 was compiled). See the pcre2_set_character_tables() page. You might want to do this if you are using a non-standard locale.
If the argument is NULL, malloc() is used to get memory for the tables. Otherwise it must point to a general context, which can supply pointers to a custom memory manager. The function yields a pointer to the tables.
There is a complete description of the PCRE2 native API in the pcre2api page and a description of the POSIX API in the pcre2posix page.