Use the compress option.
The compress option may be
specified against a data step, or on the options statement. The former
option just turns it on for that dataset, the latter for every
subsequent datastep. Using this option compresses the data against each
variable in every observation as much as possible. The use is as ;
OPTIONS COMPRESS=YES|CHAR or OPTIONS COMPRESS=BINARY.
The former option uses Run
Length Encoding to compress data (better for character data). The
latter uses the Ross Data Compress technique, which is more effective
for numeric data. RDC works on a whole record at a time, and hence a
longer record length is preferable for the dataset.
TAKE CARE : While this option
might reduce storage (there's no guarantee that it will be able to
compress the data), it is likely to increase CPU time.