This will create a database file that contain s all the jobd descriptions on the system.
DSPOBJD OBJ(*ALL/*ALL) OBJTYPE(*JOBD) OUTPUT(*OUTFILE) OUTFILE(QTEMP/JOBDS)
Now write a CL program with DCLF JOBDS (or whatever name you used when you created the above file).
Read the file with RCVF
You will probably want to check the library name (ODLBNM) to see if you want to make your change.
Now you can use CHGJOB ODLBNM.ODOBNM to make whatever changes you want to,