Hi, I have made some changes to RC_1_34_0/tools/build/v2/tools/acc.jam. With this change single/multi-threaded builds are possible but bjam still defaults to 32-bit binaries even though --address-model=64 is passed as a command line option. Also, this update doesn't require the macro *BOOST_HAS_THREADS* to be defined in boost/config/platform/hpux.hpp Would it be possible for me to specify following flag(s) for toolset *acc* and boost: 1. +Z/+z for position-independent code. 2. +DD64 for 64-bit through address-model=64. This requires the below listed toolset-tag patch. On HP-UX 11.23 for toolset *acc*, libraries are being built without the *acc* toolset-tag. This is due to the missing case statement in local rule toolset-tag {} for *acc* in tools/build/v2/tools/common.jam. Following line should fix this: case acc* : tag += acc ; # line number 691 -- regards, Prashant Thakre