port to solaris perls configured for old posix (analysed by Jost Krieger).
do our own stack memory management for threads - linux allocates outrageous amounts of VM (not so bad unless you use mlockall...), which severely limits the number of threads on 32-bit arches: stack size is the larger of PTHREAD_STACK_MIN and 4096 * sizeof (long) (usually this is 16..64k).