Photoshop reducing available ram dramatically

Hello,
I have a macbook pro (2009) running Snow Leapord
I currently have 113.64 GB of available but as soon as I open Photoshop (cc) it reduces to around 9.6 GB and is extremely slow (to the point of not functioning). I am a graphic designer, so I feel like I know my way around a computer, but I'm concerned and being overly cautious about this issue.

This is a new problem as of last night. I use photoshop daily.

Thank you for your advice and suggestions.

My understanding of Photoshop is that it creates a large block for temporary working space and needs free memory. Install as much memory in your machine as you can afford and it will take... also a new larger faster hard drive will certainly help. I believe your model MacBook Pro can accept 8 GB of memory.

OK, I'll admit I'm confused by your post. You mentioned 113.64 GB that I presume is on your hard drive, then you say "it" reduces to around 9.6 GB. What is the "it" in that sentence? Are you saying that PS opens up 104 GB of files on your hard drive? If that's what's happening, what chscag suggested won't help that. MY PS6, opened under Mavericks, writes about 2.7 Mbytes and reads 3.3 Mbytes in the boot process. If you're seeing GIGAbytes, something is fundamentally wrong with your version of PS.

So, let's have some information here: what machine, how much memory (RAM, not hard drive), how big a hard drive, what's the remaining storage on it and any clarifying data on what you originally posted.

What chscag suggested is a great idea, as PS likes a lot of RAM to use when it has files open, particularly large and complex ones, but your post seems to be referring to hard drive storage, which shouldn't happen, but if it does, might be indicating you need to get a bigger hard drive.