1. U should pass value using file from JCL.
2. U open file in I-O mode in prgm.
3. Read ur input record from that file process it and Rewrite the record of it for using next time running same ur prgm.
First time U wants to run ur prgm. With today date, second time tomorrow date,...ect.
In this case read today date from file and using for all process and finally increased by 1 day and rewrite it...!