I just launched Premiere Pro for the first time on my new PC;
I have a 500 GB SSD as primary disk, and I added a 2TB SSD disk as cache for our projects (that are stored on a NAS).
I open preferences and then I changed the cache location (both files and database) to the secondary SSD.
Then I enabled the "automatically delete oldest cache files when cache exceeds" option and then I tried to specify 1000 GB BUT it automatically changed the number to 465 (that is the space available on primary SSD).
Then I tried to confirm with "OK", reopen the settings and... I had 100 GB. It seems that the number is capped to 100 when you save.

I think that is useless to cap the max size to the space available because:
1) space available changes. I think has more sense a range than a single value (when cache exceeds 100 GB or free space fall behind 10 GB)
2) there is another cap to 100 GB.

I can understand the choice to cap to 100 GB to avoid performance hit / cache growing too much BUT I think should be a choice - I use a 2GB/s M.2 SSD and I work with stereoscopic VR360 videos so for me 100GB seems like an obsolete default.

Thank you!

Claudio