6.1 Handling Files

This chapter covers some practical aspects of programming with ACUCOBOL-GT. It covers implementation details and explains how to write portable programs.

Managing files forms the central focus of most COBOL applications. This section discusses the implementation and special features of the three types of files: sequential, relative, and indexed.

ACUCOBOL-GT supports variable-length records in accordance with ANSI standards for all file types. A file's records are variable-length whenever any one of these conditions is true:

The RECORD CONTAINS clause contains the VARYING phrase.
The RECORD CONTAINS clause contains both a minimum and maximum size.
There is no RECORD CONTAINS clause but the file's FD specifies more than one record, and those records have different sizes.

A file's records are fixed-length whenever:

The RECORD CONTAINS clause specifies only a maximum record size.
There is no RECORD CONTAINS clause, and the file's FD does not specify multiple records having different sizes.

Note that ACUCOBOL-GT automatically closes all of its files if it is killed by the user. However, a power failure, turning off the computer, or issuing a "kill -9" from the console are catastrophic exits--in these cases ACUCOBOL-GT cannot close its files.

More:

6.1.1 Sequential Files

6.1.2 Relative Files

6.1.3 Indexed Files - Vision

6.1.4 Record Locking

6.1.5 Device Locking Under UNIX

6.1.6 Indexed File Considerations

6.1.7 Converting RM/COBOL Data Files

6.1.8 Performance Considerations

6.1.9 Limits on Open Files