On IRIS version 2024.1.0.262.0 I have a table that store streams as %GlobalCharacterStream.
But depeding on the blob being saved I get the error: [Error: <<MAXSTRING>]

I had that with Caché, but to solve that I'd just enable the long strings on the page System Administration > Configuration > System Configuration > Memory and Startup > Enable Long Strings.
But for Iris I can't find that configuration, I looked on every config page from the portal and couldn't find it.