We run DB2 UDB V7.1 on AIX & the files that relate to DB2 Control Center jobs are found in the sqllib sub-directory under the DB2 Administration Server home directory. There appear to be 4 files total - db2jobht.bak; db2jobht.prf; db2jobsm.bak; & db2jobsm.prf. I'm not exactly sure which files do what (although the ones with the .bak suffix appear to be backups for the ones that end with .prf), but it looks like the db2jobht.prf seems to contain the 'history' of jobs that have been run & the db2jobsm.prf seens to contain the jobs that are scheduled. The files are 'scrambled' (not plain text anyway) & are a bit difficult to decipher.
I've not worked with UDB under Windows, but I would imagine that the files are located in a similar directory (sqllib) in that environment.