Hi Pritish,
Are you using SAS Enterprise Miner?
If I understand well, you don't want to create a decision tree model, but rather to determine the optimal split on each of your 300+ variables?
If the end goal is optimal binning using a decision tree, you can do that using the Transform node with option set to optimal binning.
If you are doing something else, you need to create a macro that calls proc arbor passing one variable at a time.
Give it a try creating your macro, happy to help if you have questions.
Arbor doc in case it helps: http://support.sas.com/documentation/onlinedoc/miner/em43/allproc.pdf
Good luck,
M