Code should not contain data other than alphanumeric.
In other words, you are saying that any one of the 256 possible characters in EBCDIC is valid for this variable -- so what could possibly be an invalid character? Answer: there are no invalid characters.
It's not clear what you want to do. Please show an example of the records in your input file (relevant fields only) and what you expect for output. Explain the rules for getting from input to output. Give the RECFM and LRECL of the input file. Give the starting position, length and format of each relevant field.