q.v. http://vergil.chemistry.gatech.edu/resources/programming/threads.html
It looks like it is up to YOU to put in the -D_POSIX_PTHREAD_SEMANTICS and -D_REENTRANT on the compile line, and specify -lpthread on the link line.
Keep in mind, C and C++ do not have a language specification for multithreading. Any multithreading facility is an "aftermarket bolt-on". POSIX threads (pthreads) attempts to make a platform agnostic / consistent multithreading experience.
There are languages that do incorporate multithreading into the language proper. For example: Ada, Java and (academic MIT project) Cilk.
HTH, --Eljay
