Adding a field to an existing COBOL data file

Question

I have an existing MF COBOL 4.0 program with years of data in a ISAM file but I need to add a new field to the existing file. The record currently has 1208 chars and I need to add another 10 to it.

If I simply put the extra PIC X(10) field in my copybook, it gives me an error.

Answer 1

With changing the copybook, you're only changing the representation of the data used in your program. Shouldn't you be restructuring the data source (i.e. the ISAM file) as well?

Answer 2

You need to modify the underlying data file to match your file definition in COBOL. One way to do so would be to define a line of output exactly like what lines of your data look like now, but with an extra Pic x(10) on the end of it. You would then read in your data line by line, and output it to a new location with 10 extra spaces on the end of it. That way your data is 10 characters longer, and you can go back and add that extra Pic x(10) to your main program. It should work after that.