Since I have root access to this box, I've got the values:

/proc/sys/kernel/shmall = 3279547
PAGE_SIZE = 4096

So based on the formula I should be able to access 12GB:
(3279547 * 4096) / 1024/1024/1024 = 12 GB

I'll read the link you sent and see if there is anything that I'm missing.

Thanks
Randy