Opened 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 then controls how the program and the system interact. You have two options regarding how your application program uses the file description:

• You can use the file description as it currently exists. In this case, the system uses the file description as is, without any change.

• You can change some or all of the parameters that are associated with the file description. A change made to a file description can be permanent or temporary. See the appropriate book for the device that you are using for information about permanent changes.

• 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).

• Opening files using temporary file descriptions
  Temporary changes can provide greater flexibility to the application. The system 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.

• Detection of 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.

• Displaying 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.

• Monitoring file status with the open and I/O feedback area
  The system monitors the status of a file in feedback areas once it has successfully opened the file.

 

Parent topic:

Working with database files

 

Related concepts

File types