Hi,
I have been told, that I should not choose Hibernate, if database is also manipulated or queried without Hibernate(for example db2 database is also accessed/updated via procedures written in COBOL on z/OS). Is this true and why?

Thomas

I would not say it is true.
When Hibernate operates without 2nd level cache and an application does not use long running Hibernate sessions, then using Hibernate is not different than using any other DB interaction technique including straight JDBC.

Hibernate can be tuned to assure data accuracy, see for example:
http://www.hibernate.org/hib_docs/v3/re ... tions.html
http://www.hibernate.org/hib_docs/v3/re ... ns-locking