location of jam executable

hi, i d/l'ed the 1_27_0 and have successfully built the jam executable. i went through the documentation for build but am still unclear as to the location from where jam should be run. do i just copy jam into the top level directory where the files were extracted to and run it from there after setting BOOST_ROOT? some posts in this list conveyed the impression that it should be run from within the source library for each library. i find that confusing. isn't it the intent(?) of jam to be able to build the code wherever it may be located provided that the appropriate entry has been made into BOOST_BUILD_PATH/BOOST_ROOT? i apologize since this post is probably somewhat off-topic. sincerely, abhishek.