Dear Mr Ostrop,
according to the documentation for IBM i 7.1 at the IBM Knowledge Center, the only 2 GB limit exists when accessing a system at IBM 6.1 or earlier through QFileSvr.400. When working locally on IBM i 7.1 in the root file system or accessing a file on IBM i 7.1 or higher through QFileSvr.400, the limit is 128 GB for "Type 1" stream files and 1 TB for "Type 2" stream files.
The error message "Value too large to be stored in data type" sounds more like an error in the application than a limit in the file system.
Kind regards,
Christian Bartels.