[boost] [thread] Memory usage of threads on 64bit linux

Hey, I have been using boost threads on 32bit linux for some time and am very happy with their performance so far. Recently the project was moved to a 64bit platform and we saw a huge increase in memory usage (from about 2.5gb to 16-17gb). I have done profiling and found that the boost threads are the source of the huge allocation. Each thread is allocating about 10x what it was doing on 32bit. I profiled using valgrind's massif and have confirmed the issue using only boost threads in a separate test application. I also tried using std::threads instead and these do not exhibit the large memory allocation issue. I am wondering if anyone else has seen this behaviour and knows what the problem is? Thanks --