The unsigned integer format is like the integer format except that the range of values does not include negative numbers. You should use the unsigned format only when non-negative integer data is expected.
You define an unsigned field by specifying the UNS
keyword in a free-form definition, or by specifying U in the Data-Type entry of
the appropriate specification. You can also define an unsigned field using
the LIKE keyword on the definition specification where the parameter is an
unsigned field.
For other considerations regarding the use of unsigned fields, including information on alignment, see Integer Format.