What's the GPU memory requirement?

Hi,

I want to begin mining on some (considerably old) machines I own.
Since Ether mining requires more than 2GB of GPU memory and it only keeps growing, and some of the GPUs I own only have 2 GB of memory, I immediately turned to consider Zcash as a worthy alternative.

What's the GPU memory requirements for mining Zcash? Can I mine on 2 GB GPUs?
Which miners are recommended for old machines (with 2GB or lower GPUs)?

Thanks a lot,
Moshe