How hard would it be to include in the back-end programming to "take from the smallest stack" of items when you're crafting?

i.e. I've got 170 uncooked chickens, 1 stack of 100 and 1 stack of 70 - and it seems every time I craft, it will start using chickens from the 100 stack and not the 70.

Meaning you've got to re-stack items constantly, and when bag space is limited this is quite annoying.

Thanks,
UMP