1. A method of producing a job flow specification by determining a sequence of execution of respective load modules and a file input/output distinction of each of at least one file to be used in job control language by analyzing the job control language and a source program and producing a job flow specification in graphic representation including a sequence of execution of programs in a job and the file input/output distinction of each of the at least one file with the aid of a computer, the file input/output distinction indicating whether each of the at least one file is to be input or output, the method being executed by a computer and comprising the steps of: preliminarily storing utility program information, the utility program information including a utility program name to be used in said job control language, a file name thereof, and a file input/output distinction; analyzing said job control language with the computer; determining, from the stored utility program information, whether a load module name obtained in the step of analyzing said job control language is a utility program name; determining a file input/output distinction of each of at least one file to be used by a utility program having the utility program name from the stored utility program information; and producing a job flow specification for a load module having the load module name determined to be the utility program name based on at least the file input/output distinction of each of the at least one file to be used by the utility program having the utility program name.