job name not known error

In HP-UX when trying to suspend (CTRL-Z) a process/job or when running a job in the background i.e: sleep 30 &   then running the jobs command, if you get message: <job name not known> then you'll need to defined the HISTFILE and HISTSIZE variables to fix the issue.

$ sleep 30 &
[1]     19870

$ jobs
[1] +  Running                    <job name not known>

or suspending the running command with CTRL-Z

$ sleep 20
[1] + Stopped                     <job name not known>

fixed by setting HISTFILE and HISTSIZE:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=200334 (ITRC login required)

export HISTFILE=$HOME/.history
export HISTSIZE=2000

$ sleep 20
[1] + Stopped                     sleep 20