The BACKUP utility has the ability to compress data it places in a saveset. This is enabled using the /DATA_FORMAT=COMPRESS qualifier.

$ directory /size /total *.com

Directory $22$DKA300:[WILLIAMS]

Total of 82 files, 6983 blocks.
$ backup *.com my_com.bck /save
$ backup *.com my_com_compressed.bck /save /data_format=compress
%BACKUP-I-COMPRESS, data compressed by 83%
$ directory /size my_com*.bck

Directory $22$DKA300:[WILLIAMS]

MY_COM.BCK;1                                 7938   9-MAY-2007 14:13:38.07
MY_COM_COMPRESSED.BCK;1                      1410   9-MAY-2007 14:14:30.22

Total of 2 files, 9348 blocks.