Try a NSLOOKUP 'xxx.xxx.xxx.xxx'
where that is the cifs IP address. You may get something like:
Which is my PC name. If you name your PC's meaningful or have a table of
who is using which PC that may help.
Here, GDL164 may have their 5250 session equal to GDL164S1 and an object
lock on that, config status, etc, may help determine who that is.