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Provide a method to allow OS/390 programs using Sequential Input/Output to execute in the Virtual System Environment (VSE) system by converting the OS/390 Data Control Blocks (DCBs) to the VSE Define the File (DTF) at execution time. Disclosure Number: IPCOM000014216D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2003-Jun-19

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CD Rom reference SK2T-0730-22 The OS/390 operating system uses Data Control Blocks (DCBs) to define datasets within programs. In VSE, the equivalent definitions are called Define the File (DTFs). However there is not a one to one relationship between the two formats, so DCBs cannot be used on a VSE system. Programs written to execute on an OS/390 operating system which use Sequential Input/Output (Sequential I/O) need to have their datasets defined using DCBs. Input/Output operations cause the DCB to be updated with information which is interpreted by the program. In a VSE Operating System, programs use DTFs to define files (which are the equivalent of the OS/390 datasets). Sequential I/O operations cause the DTF to be updated. The DTF layout is very different from a DCB and does not contain the same fields or information. So a program written for the OS/390 system which performs Sequential I/O operations cannot be executed on a VSE system without the entire Sequential I/O code be rewritten. This solution provides a means whereby only the macro names and a few additional parameters need to be added to the OS/390 programs to allow them to perform Sequential I/O operations in a VSE Operating System.