Perl-совместимые регулярные выражения (Perl-compatible regular expressions)
HANDLING VERY LARGE PATTERNS
Within a compiled pattern, offset values are used to point from
one part to another (for example, from an opening parenthesis to
an alternation metacharacter). By default, in the 8-bit and
16-bit libraries, two-byte values are used for these offsets,
leading to a maximum size for a compiled pattern of around 64K.
This is sufficient to handle all but the most gigantic patterns.
Nevertheless, some people do want to process truly enormous
patterns, so it is possible to compile PCRE to use three-byte or
four-byte offsets by adding a setting such as
--with-link-size=3
to the configure command. The value given must be 2, 3, or 4. For
the 16-bit library, a value of 3 is rounded up to 4. In these
libraries, using longer offsets slows down the operation of PCRE
because it has to load additional data when handling them. For
the 32-bit library the value is always 4 and cannot be
overridden; the value of --with-link-size is ignored.
