Upload & Sell: On
psd has a maximum size of 2 gb
tiff has a maximum size of 4 gb
psb, also known as Large Document Format has a pretty much unlimited size limit
If you're going to be close to the limit to any of the limited formats, Ps will usually try and warn you and not let you save, as the file would not re-open otherwise. The only way I know to save in psb format is to actually choose that as an option, which you may have done my mistake. No harm done.