[Boost-users] enable thread safety

Hello, I am building boost regex using VC6, and I am not sure BOOST_HAS_THREADS is enabled by default or not. Reading http://www.boost.org/libs/regex/doc/thread_safety.html, it doesn't tell me which file to look, and how to enable it under VC6 if disabled by default. Could somebody help me on this please? Thanks! /Winson