V6R1 is the next major release for i5/OS. This one has a lot of changes and improvements. On the other hand, it needs object conversion as well. Therefore, you should prepare for this release.
IBM is providing current information how to upgrade to V6R1M0 on a special infoapar. The Information Apar is: II14310
It can be viewed at: II14310
As this Upgrade to V6R1 needs a type of object conversion as it was known from V3R6 from the RISC change, it would be advised to check more in detail, if all programs are really supported and possible to be converted on V6R1.
Fortunately ALL programs, that are created for V5R1 or higher ALWAYS are possible to run on V6R1 ;-)))
(IBM prevented the deletion of the observabilties with CHGPGM since V5R1 - even when this is still possible internally it only compresses the observabilities. That was a very wise decision at that point of time.)
For preparation for the V6R1 upgrade, IBM created the new Redpaper REDP-4293.
This one is available at:
Redpaper REDP-4293 in HTML in the web
Redpaper REDP-4293 as PDF in the web