If you use the LSB of the last byte for a flag, you're using the 56th bit of one of the {data,size,cap} words. I'd use the MSB in this case, since you can shift

If you use the LSB of the last byte for a flag, you're using the 56th bit of one of the {data,size,cap} words. I'd use the MSB in this case, since you can shift that off easier.