Hello and welcome to the forums,
You need to clarify your question. . .
VSAM is used in many systems to provide keyed access to data. DB2 is a database system. If your code uses VSAM definitions/commands, those are not "in DB2". DB2 uses SQL, not the commands used in VSAM.
Once your question is better understood, we will probably be able to provide more useful replies.
Hope this helps,