Basically, the data is migrated from VSAM to DB2. But the programs do not have to change. The CICS VSAM Transparency offering consists of a set of conversion tools and a run-time management control component. The conversion tools include all the utilities required to convert VSAM KSDS and RRDS structures to DB2 tables, build the static SQL drivers and migrate the data. The run-time component evaluates the application program's original and unaltered VSAM calls, processes them in DB2, and returns the results to the calling program.
This is a workable solution for a quick and dirty migration of VSAM data into DB2. It is really not the best solution though, because the data in most VSAM files could benefit from normalization as it gets moved to DB2, and you might encounter some performance issues that you would otherwise not face with a full-blown migration of both data and programs. That said, the migration of program code can be very costly and time-consuming, and a product like CICS VSAM Transparency can mitigate those concerns.
This was first published in June 2006