Size limit on TIF Files in Photoshop CC

OK, I see the logic but I'm struggling with the idea that the designers built in a 75% comfort margin. Any file above 1GB is being refused against a stated maximum of 4GB.  It also looks to me as though Photoshop does know the size of the file because it goes 99% of the way through a TIF save before declaring it too big.  Since this doesn't seem to be a common problem I suspect it's something very simple I have wrong in my settings or system.  Like searching for the Holy Grail...possibly a long and fruitless journey!

Until I find a solution I have adopted an idea found on another forum which  at least  allows psb files to be "visible" in Lightroom.  I will list the method here in case it is of use to someone else and because I was able simplify things and omit a number of steps without apparent problems;

1. In PS create a new document then File>Place Linked and point to the psb file thereby creating a smart object which will automatically synch with the big document file

2. Save the new PS document as a TIF file in the same directory as the original psb then open LIghtroom and synch that directory so that the image is visible in the library

3.  You can now open the TIF file in Lightroom and send it to PS for editing in the usual way.  When the TIF loads into PS click on the smart layer and the psb file will open for editing.

Hi.  Here is the information for one sample file; pixels 9928x5960, bit depth 16, 21 layers in five groups including one smart layer (a duplication of the base layer) with a filter applied.  Photoshop (in the border ribbon) shows the image size as 339M and the file size as 1.5GB.  As saved the size of the psb file for the same photo  is 1.8GB.  It is happening with almost all files in which pixel layers are added.  

I see your point. Sorry, I wasn't clear.  When I reluctantly accept the option to save it as a psb then it's the size of that file I referred to.  I assumed the TIF file, if it could be saved,  would be no larger. In addition, Photoshop is also showing the  file size, as I work it up with additional layers and before attempting to save it, as well below 4 GB.