Problem:

When compiling a COBOL program that contains copybooks that is greater than 256MB, the compiler returns the following error even though the copybook exists and is case sensitive:

*    2  copy "<copybook name".

*   8-S**************************  (0)**

**    Unknown COPY file <copybook> specified

Resolution:

The reason this is happening is because the total limit for a COBOL program data division is 256MB. The compiler would only have opened the file and read the first x number of bytes. A too large data division would get a clear message indicating that fact. The file is so large the CBL_OPEN_FILE or CBL_READ_FILE has failed and returned a non-zero file status, hence the error.