Systems engineering prescribes a rigid process of systems development from well defined requirements to the verified and validated resulting system. This process only partly is and can be followed in information systems engineering. First, the information system is a socio-technical system, therefore it is impossible to fully engineer it. Second, frequent changes in information system can rapidly cause its deviation from the initial design even up to losing its systemic properties to some extent. For instance this can happen by using agile methods in an uncontrolled manner. The paper claims that systemic properties of information systems should be analyzed at any stage of systems life cycle. The Viable Systems Model and consideration of ecosystemic dependency are proposed as means for continuously assuring systemic soundness of engineered information systems.