A column's length refers to
the number of bytes used to store each of the column's values in a
file. For example, a column that is defined as a DOUBLE has a storage
size of 8 bytes.
In SAS, you can control
the length with the LENGTH statement in the DATA step. However, the
LIBNAME engine does not support specifying a shorter numeric storage
size with the LENGTH statement. When you use the engine, you can read
a legacy SAS file with a shorter numeric storage size, but you cannot
specify a shorter numeric storage size or update the data.