Thanks for the information, Frank..
I am aware that if the records are already sorted, we can use MERGE instead of SORT which is efficient. Unfortunately not all the files we have are sorted.
Over the period, I have learned that just knowing various SORT operators / options isn't enough. But how to use them creatively to solve the problem at hand, is something one should be able to do. And your's and Kolusu's exmaples on various forums teach us that thing.