I asked you to do some reading from chapter 10 of the manual. I agree that is is not clearly stated, so I have pasted the information:
A question mark in the last input column of a data record indicates record continuation.
And in section 10.2:
For fixed-length records, the last eight character positions are considered to be a sequence number. The character preceding the last eight characters is considered to be the last input column.
So, for an LRECL=80, put a question mark in column 72. It worked for me.