If you look at the Bundle Definition Attributes screen, there is a field entitled "Job Statement Information". If this field contains JOBCARD statements, then RMOSTC will submit a batch job to process the bundle.
However, if you leave this field EMPTY and do not code JOBCARD statements, then the bundle will be processed/created by the bundle output task (BOT), without the submission of a batch job, and the bundle will appear under the RMOSTC task itself.
If you access the Bundle Definition Attributes screen and then type HELP in the command line, you will find the following excerpt in the help text information:
(11) - Job statement - the job statement (comprised of 1-4 card images) to
be used to submit a batch job to create the bundle. If the job
statement information is left blank, then the bundle will be created
directly by the bundle output task without the submission of a batch