These variables indicate whether the filesystem you are accessing with the the EXTFH interface can or cannot handle variable length files. Setting this variable to the default of 1 (on, true, yes) causes the EXTFH interface to pass the minimum and maximum record lengths to the file system for variable length files as defined in the COBOL program. Setting this variable to 0 (off, false, no) causes the EXTFH interface to ignore the variable record length defined in the COBOL program and instead pass a record length equal to the maximum record length.
You can specify the variable separately for indexed, relative, and sequential files. For example:

When the file system does not process variable length files, set these configuration variables to "0" and the EXTFH interface treats variable length records as fixed lengths.

If the file system does process variable length files, set the configuration variables to 1 (or do not set them at all).