In Db2 12, it was introduced that a userid must have atleast SYSOPR
authority to be able to STOP and/or START Db2 and perform DISPLAY
commands from the system console.
In order to GRANT SYSOPR authority to GROUP1 you can run
DSND10.SVSC.CNTL(GRANTOPR) from IBMUSER or another userid
that has SYSADM authority on DBDG. If you want to do the grant to
a different RACF Group or a particular userid, you can change the
grant statement in the job to meet your needs. Remember you cannot
save changes in this dataset, so edit, make your changes, submit and
then cancel.