Is there a max size to JMS message size in ActiveMQ "Classic"?

Question

All I could find is that there isn't a specific limit to message size, but it's dictated by the heap memory allocated to the JVM. Anyway smaller messages are better. I'm trying to send a 1Gb file with ActiveMQ "Classic" without running into out-of-memory errors. I've read that the guys using ActiveMQ Artemis managed to do 8Gb using 50Mb of ram, but it takes me at least 4Gb to send 1Gb (using the "blob" message from ActiveMQ "Classic"). Anyone has any idea why?