3L does do this. You can share as much data between the OS and user applications as you want. The OS doesn&#x27;t really mediate anything so there is no overhead from copying data or messages between processes or enforcing some security mechanism. The language runtime enforces the references that are available to some code that gets run but that&#x27;s it and that&#x27;s all that is needed. You really don&#x27;t need a separate OS program facilitating everything to serve as an OS.