I don't know how others do it, but I know I'm not the only REXXer who's written such a utility. The way mine works, you put the command (I call it "DISP") in front of any TSO command—almost any TSO command—and it executes normally but displays the output in a View session instead of TSO's "line mode".
So, for example, instead of
tso tss list(victim) data(xauth)
...I would type
tso disp tss list(victim) data(xauth)
The DISP command turns on the TRAP facility, executes whatever the rest of the command is, then copies the trapped output to a temporary dataset and fires up View to display it.
Others way have other ways of doing it. I never knew about this TSS variant.
Oh, I said "almost any TSO command"; apparently there are some programs that write their output in some form that can't be trapped in the usual way. I've heard a term ascribed to this kind of output; "WTOR", maybe? I forget. Anyway, it works with all but a few commands, not just TSS.