very_old_stack_bl  130 gc/blacklst.c      word * very_old_stack_bl = GC_old_stack_bl;
very_old_stack_bl  137 gc/blacklst.c      GC_clear_bl(very_old_stack_bl);
very_old_stack_bl  139 gc/blacklst.c      GC_incomplete_stack_bl = very_old_stack_bl;