In RBS the key word OPTIMAL is used to shrink back the extents if exceeded OPTIMAL limit and going towards MAXEXTENTS. It's very useful to cut down unnecessary space usage. Yeah, if you don't mention OPTIMAL then it will go on increasing towards the MAXEXTENTS and will not decrease unless you issue the SHRINK command.
You cannot succeed if you fear to face challenges.
MAS
BE(CS) , OCP 8/8i.