Open files

When you want an application to use a file, you do so by referring to that file by name. The file description for that file will then control how the program and the server will interact.

• Scope of opened files
  Files that are opened within the user default activation group are scoped to the call level number of the calling program (default). A call level number is a unique number that the server assigns to each call stack entry. Files that are opened within a named activation group are scoped to the activation group level (default).
• Open files using temporary file descriptions
  Temporary changes can provide greater flexibility to the application. The server makes temporary changes when the program is first establishing a path to the file by opening the file.
• Open considerations when using *LIBL with a DDM file
  There are certain considerations when you open DDM files and specify *LIBL for the library.
• Detect file description changes
  When a program that uses externally described files is compiled, the high-level language compiler extracts the record-level and field-level descriptions for the files referred to in the program and makes those descriptions part of the compiled program. When you run the program, you can verify that the descriptions with which the program was compiled are the current descriptions.
• Display information about open files
  You can display information about your open files by typing dspjob option(*opnf) on any command line and press Enter, or by typing wrkjob option(*opnf) on any command line and press Enter.
• Monitor file status with the open and I/O feedback area
  The server monitors the status of a file in feedback areas once it has successfully opened the file. As the server performs operations on a file, it updates the feedback areas to reflect the latest status. These feedback areas give you greater control over applications and provide important information when errors occur.