PURPOSE: To attain the immediate search for a system library file by starting an exclusive processor which is loaded in a job pack area in case the module whose start is designated is equal to a system program in an initialization mode.

CONSTITUTION: A module identifying part 2 refers to a table 3 to discriminate whether a module supplied from an input part 8 like a keyboard is equal to the module stored in a system library file 10. An exclusive processor (program) which searches the file 10 only is stored in a storage part 6 and then stored in a job pack area 5 of a main memory 4 in an initialization mode of the system by a system starting program 7. In such a way, the exclusive processor is immediately started to search the file 10. Then a designated program is extracted and loaded onto the memory 4 for data processing.