Source Statement Libraries and IBM System/370

The purpose of the source statement library which resides on a DASD is to aid in creating, debugging and maintaining working programs. In the past, the programmer writes and submits his program on punchcards using source statements to a translator which produces a working object module, if possible, and a listing and error statements, enabling the programmer to alter his original submission. Each time the programmer has changes to make, he resubmits the entire set of source statements, amended to reflect these changes. This is true whether he has a new program he is debugging, a correctly translated program which is not running properly or a functioning program which is to be modified to meet new standards. The source statement library provides a complete copy of the source code immediately available as a system resource. Using simple edit statements, the programmer can make temporary or permanent changes which alter this program before it is submitted to the translator. The obvious advantages of this technique are: •-testing and debugging of modifications and changes does not require the existence of a deck of cards to be manipulated by the programmer; •-temporary changes can be made without altering the library copy; •-multiple modules which comprise the program can be combined, each with or without alterations, to facilitate testing of the whole; •-temporary changes in an existing module can be done without detracting from the availability of the module.