PURPOSE: To eliminate the need for stopping a job and to shorten a system shutting down time in the case of raising the level of this system by executing an introduction/maintenance to a system data set managed in a generation by a data set name on the same system.

CONSTITUTION: An introduction/maintenance processing P2 is executed to only a data set group 12A prepared by an environment setting processing P1. Also, the name of a system data set group 12B of a new generation after the introduction/maintenance processing P2 is changed to the original name in the case of restarting the system. Thus, the shut down of the job eliminated during the introduction/maintenance processing, and th system shutting down time at the level up time of the system can be shortened.