In the Layout Definition Utility, you can specify the data format for the input and the output files.  There are three options:

Precautions when Changing the Data Format

If you change the selection between Data File Format, CSV Format and XML Format, previously-defined layout definition information may be lost.
When you convert from CSV Format to Data File you need to input the positions and item lengths for all the items.  It is often easier to re-analyze the COBOL COPY library than to change the data format.