Dear Boosters! As I am still trying to figure out how to use the thread local storage pointer I found another strange behaviour. Perhaps I am misunderstanding the docs, or this might be a bug. System: VC6.0 CVS Head Problem: When using release on a tss variable, the associated automatic cleanup routine seems not to be updated correctly as it tries to delete the original pointer, instead of the 0-pointer. Example (simple modification of tss.cpp example): boost::thread_specific_ptr<int> value; void increment() { int* p = value.get(); ++*p; } void thread_proc() { value.reset(new int(0)); // initialize the thread's storage for (int i=0; i<10; ++i) { increment(); int* p = value.get(); assert(*p == i+1); } //******** added the following two lines int* p = value.release(); delete p; // deleting the released pointer //******* } int main(int argc, char* argv[]) { boost::thread_group threads; for (int i=0; i<5; ++i) threads.create_thread(&thread_proc); threads.join_all(); } In the debug version the program faults at exit, as the pointers are beeing freed a second time. I suspect the problem lies in the following function, as it does not set the cleanup handler if the value is 0 bool tss::set(void* value) { if (value && m_cleanup) { cleanup_handlers* handlers = get_handlers(); assert(handlers); if (!handlers) return false; cleanup_info info(m_cleanup, value); (*handlers)[m_key] = info; } return !!TlsSetValue(m_key, value); } Regards, Roland Schwarz