Getting 'Error: ORA-03113: end-of-file on communication channel' error.

Issue

• We need Red Hat to review the database server configuration to increase the SGA to 8GB as needed to increase the Stream Pool Size to support for Oracle DB.
• The database is getting an error, “ORA-03113: end-of-file on communication channel”, with any SGA setting beyond 6GB.
• Database team is saying this happens (this error 'ORA-03113: end-of-file on communication channel' occurs) ONLY when increasing the memory above 6Gb. So it clearly indicates that there is some issue with the memory on the boxes and not the Oracle. Can you check if there is any memory problem ?