pcre_refcount man page
PCRE — Perl-compatible regular expressions
int pcre_refcount(pcre *code, int adjust);
int pcre16_refcount(pcre16 *code, int adjust);
int pcre32_refcount(pcre32 *code, int adjust);
This function is used to maintain a reference count inside a data block that contains a compiled pattern. Its arguments are:
code Compiled regular expression
adjust Adjustment to reference value
The yield of the function is the adjusted reference value, which is constrained to lie between 0 and 65535.
There is a complete description of the PCRE native API in the pcreapi page and a description of the POSIX API in the pcreposix page.