Should it be 'drink stall' or 'drinks stall' ?Should it be 'vegetable stall' or 'vegetables stall' ?
In general (meaning there are exceptions) adjectives don't inflect for number. So,
a drink stall
a vegetable stall
However, given the structures here,
a stall that sells drinks
a stall that sells vegetables
you might assume, or even hear,
a drinks stall
a vegetables stall
They're non-standard. (I've heard the former, not the latter. Give it time though. )
All the best.