This is an old thread and has been answered before, but I'll reply my 2c again
I've done a lot of research into this and now I ALWAYS use Open and Close around my selects and Fetch Next
The reason?
Memory
If you add a simple Fetch Single in your code and then look at you log it does open, select, fetch, close for you automatically
When you do a Select, the data has to be stored somewhere right? Well it's stored in the memory allocated to the job running. Be that BSFN, UBE, APPL.
You perform a select and the records come back into memory, you then do a fetch and the job starts to leaf through the records selected and saved into memory. (A little more complicated than that, but that's the gist of it)
So, if you don't
close that selected data down, all those records stay in memory.
Now this maybe ok for UBEs etc that will usually end anyway (then all memory is freed) but if it's a subsystem or an application screen someone uses for hours on end, then it doesn't get cleared down.
It takes a few mouse clicks to do the Open+Close
Questions you should be asking is, why have JDE given us the option of using them if they are not needed