Memory-based session storage is typically used to maintain a high-performance FIX session when persisting of a sessions state and messages to the file system is not required.
To create such a session the storageType parameter in OnixS::FIX::Session::Session constructor has to be set to OnixS::FIX::Session::MemoryBasedStorage value.
Session initiator(TARGET_COMP_ID, SENDER_COMP_ID, VERSION, &listener, Session::MemoryBasedStorage);