Long-Short Leverage

Hi there!

I am a newcomer, and I would like to operate long-short strategies. I am a little confused about margins and buying power. Let me explain what kind of info I would like to know:

Suppose I have US$ 100k in cash and made the following operations:
short-sell US$ 10k of A-stock
buy US$ 10k of B-stock

At EOD I still have US$ 100k

Cash + “B-stock” (buy side) are potential collateral for the “A-stock” (short-sell side of the operation).
How many operations like this could I do using my initial US$ 100k?

Thanks in advance.