Technical Blog Post
Why db2look is not picking up some of the objects under "SYSTOOLS" schema like "SYSTOOLS"."STMG_DBSIZE_INFO"
Usually db2look ignores the DB2 internal objects as it can recreate back those objects on it's own.
The user defined objects are more important to extract as DB2 don't have any knowledge about how to regenerate those back otherwise.
SYSTOOLS schema have mostly system defined objects. So db2look will ignore all objects under SYSTOOLS schema except user-defined functions and stored procedures.
Also, from source level to destination level the internal objects might have minor differences. That is another reason why those are ignored. Otherwise, those can cause issues while recreating back in the destination place.