The table size values that you see in Tool #1980 Library Dashboard represent much more than just # of records. It’s the size of literally everything about that table in the database – name, description, or other backend “metadata” items which are used to define a table and use it for processing. Changes in size on any or all of these items are often simply part of system processing and to be expected.
As an example, let’s say you have a table called MBRLIST1 and you make a copy of it called MBRS1. At a basic level, the loss of 3 characters equals a decrease in size of that table’s footprint in the database. 3 characters does not equal 3 bytes, or even 3,000 bytes necessarily, but the take-away is that some of the minor things we normally don’t think about do actually affect table size.
Remember, there are other elements about the table that are affected. It is normal to see table size values changing slightly on both sides during the copy action. The table that was copied may see its size increase very slightly. The table that is now a new table will almost always be slightly smaller, even with identical name, description, and # of rows. Both results are normal.