Iteration between two stacks

[gprieto at usal.es]

Having two satcks, one for generate some variables and other to save them.

After the first run, the variables must be saved in the "second" stack and
the "first" stack must be go to its first card.

How can I program an iteration between these two stacks, in a manner that
when the "first" satck goes to its first card, the other one save and
close?

Gerardo