I think the question you are asking is, what will your next year's cap number be for the rest of this year if you release a player with an option next year?
I think the answer is: if no one picks him up, the full salary (although after rollover you will be assumed to drop the option and not charged the full salary when next season comes). If he gets picked up, just the option number, I think. I don't know what would happen if you cut him, he clears, and then you re-sign him.