If the number of source variables are greater than the number of destination variables declared and "ON OVERFLOW" or "NOT ON OVERFLOW " is not specified .then whether the prgram gets abended or it will populate the last destination variable with the entire left out part of the string .
UNSTRING FullName DELIMITED BY ALL SPACES
INTO FirstName, SecondName, Surname
Full name = "John Joseph Ryan chennai"
first name = john
second name = joseph