Getting values from stack

[Francesco]

Hi to all
I'm new in HP PPL programming. I wrote a simple program that have as inputs two variables:
EXPORT myprog(value1,value2)
BEGIN
....
END

and it works fine. Running this program appears two edit box for variable insertion. How can I get these variables from stack ? That is I insert two values on stack and I want to give them as input to myprog.
regards