Once, long time ago, there was a very old dinosaur living on the planet Earth. Big yet invisible to most, living in the dark places full of cold, dust and cables; surrounded by several groups of faithful - very specialized software teams, the only ones who truly understood him. But the life on the planet Earth had never been steady and recently spinning faster and faster around, so it happen that even this group had to be changed and follow the fast changing business environment outside, unless they all die. And here our story begins. The story is based on our experiences from multiple companies and projects operating on high-performing applications environment - mainframes. The companies are mainly from banking services, insurance systems and other very specific software industry areas where mainframes are still very popular.