Mike,
Thanks a lot for your help. This is indeed very helpful. I have gone through the note 498223 where it says:
The stock of the storage location in R/3 corresponds to the actual fill level of the resource with
storage characteristics in APO.
I believe this means I would be able to monitor fill level only after I do the goods posting. However this was not my requirement. I wanted the system to throw an alert when the operational quantity of the planned order exceeds the storage capacity of the resource. This requirement cannot be addressed by this alert it seems.
Thanks again for your inputs