Maximum Qty of Material

Can we specify 'Maximum Quantity of a Material' anywhere.

Suppose i have a Material in Stock of 100 qty.

And Still to deliver (open PO qty) = 250 qty

And a new PO is created again for 200 qty. I want to block the creation of PO when, stock qtyopen po qty qty in new PO exceeds 500 .

Is is possible, pls help.