Our TNS listener is consuming a lot of memory. I have Oracle 18.104.22.168 on a Unix box that this is consuming a lot of memory and it is increasing. The interesting thing is that when I shut this service down it's consuming low memory. Have you any idea of the root cause of this issue?
This sounds like a memory leak in the Listener process. I run Oracle 22.214.171.124 on Solaris and I have never noticed this behavior. So I suggest you contact Oracle Support for a resolution. Alternatively, you can upgrade to Oracle 10g to see if this solves the problem.