THRNUM_SHIFT
alloc->next_id <<= THRNUM_SHIFT; /* of *_id is used. */
alloc->last_id <<= THRNUM_SHIFT; /* or implicit 'int' ops. */
alloc->next_id <<= THRNUM_SHIFT; /* in steps for comp. */
alloc->next_id <<= THRNUM_SHIFT; /* of *_id is used. */
alloc->last_id <<= THRNUM_SHIFT; /* or implicit 'int' ops. */
alloc->next_id <<= THRNUM_SHIFT; /* in steps for comp. */