I used DYNCOPY to copy a file using BLKSIZE/OBLKSIZE and FORMAT=U, but the resulting file have a block size of 32760, so I'm missing data's.
When the input of a DYNCOPY is not a catalog controlled dataset, it checks the input card to see if a record length was specified. If not specified, we default block size to 32760.
For example to copy a FAVER2 output tape, the command will be:
"COPY,BLKSIZE=56664,OBLKSIZE=56664,RECFM=U