Simultaneous Equations Model

[leeiq]

I have a questions on Simultaneous Equations Model implementing using SAS,

x = f(y, z1, z2)

y = f(x, z1, z3)

I tried to use 2SLS in proc model to estimate, however it seems that SAS implement them separately and get two R^2 for each model, is that a way to estimate simultaneously and get a system-wide R^2?

Hope anyone can provide me the answer, I really appreciate that.

Thx