PURPOSE: To eliminate necessity for considering validity or the like in the case of registering a load module on an executing system environment or updating the load module by designating the validity of the load module in the case of preparing the load module, and checking it in the case of execution.

CONSTITUTION: When preparing the load module, the date of validating the load module to be generated and a date 2 of expiration it are instructed and inputted to a linker 1 in addition to normal link information. The linker 1 outputs a load module 3 after adding the inputted validity information to normal management information. When executing the load module, the load module having the date of a start instructing time point settled within the validity information is retrieved from the single or plural load modules existent in the executing system environment corresponding to an instructed load module name and when such a load module exists, the load module is executed. When there is no load module corresponding to the validity, it is informed of a user.