Hi Ron,
If you want to opt EOIO for single stack, check:
Flexible Serialization in SAP PI
Achieving Serialization Behavior in Typical Asynchronous Interfaces
As you know, all the messages would get stuck for a single error or failure in EOIO communication. You may want to check:
How to deal with stuck EOIO messages in the XI 3.0 Adapter Framework
Regards,
Nabendu.