Appendix D - Size and Precision Handling

During JSON PARSE processing, the JSON value may exceed the size, length or precision of the matching COBOL data item. When this occurs, the operation continues with a loss of significance, and reason code 128 or 256 may be set in the JSON-STATUS special register. If the WITH DETAIL phrase is specified, a run-time message may also be produced.

JSON-STATUS special register value 128 and 256

The JSON-STATUS special register is set to the following values in the following circumstances:

Signifies a loss of precision when matching a fixed-point integer, fixed-point non-integer, or floating-point JSON value to the COBOL item. This occurs after decimal point alignment, when the JSON value exceeds the value that the COBOL item is capable of holding. JSON string values containing only digits can also cause this value to be set.
Signifies a loss of information from a JSON string value.