[boost] Building Boost On Tru64

Hi, I´m trying to build boost_1_31_0 on a Alpha box running Tru64 version 5.1B. After running bjam "-sTOOLS=gcc" stage I get the following error: /usr/include/pthread.h:328:4: #error "Please compile the module including pthread.h with -pthread" Since I´m a newbie to boost I´m looking for some help to handle this issue. Best regards, Eduardo