Re: SYSOUT vs. QPRINT for debug-type information... -- COBOL400-L

cobol400-l-request@xxxxxxxxxxxx wrote:

   1.  SYSOUT vs. QPRINT for debug-type information...
      (Michael Rosinger)
Another ILE/COBOL newbie question. I was running a test program where I wasissuing a lot of DISPLAY UPON SYSOUT messages for debug purposes. The jobwas cancelled by the system because "the size of the message queue for jobxxx reached the maximum size". I see from the output that in addition to thelines I was interested in seeing there were lots of system-generated stuffthat I did not care about.

Other posts have hit most point related to this. I just wanted tobring elements together in a single place.

Your DISPLAY statement results in a message being sent to your job'smessage queue. The size of job message queues is controlled in orderto limit runaways; pretty standard stuff there.

Control is done on general size at the system level by two systemvalues -- QJOBMSGQFL and QJOBMSGQMX. Those values can be overriddenfor any particular job by job attributes from the job description,from the SBMJOB command or, in the case of QJOBMSGQFL, from a CHGJOBcommand.

Further control can be done with the LOG() parameter of SBMJOB orCHGJOB or the LOG() attribute of the associated job description.This can be used to limit _which_ messages make it into the jobmessage queue. Selection is done by message levels and severities.

By having a large job message queue size and only allowing yourDISPLAY messages into the job message queue, you can manage tocreate a _very_ long list of messages, tens of thousands easily.

And by specifying "*PRTWRAP" to be the action that happens when thatmessage queue gets full, you can flush the message queue out to aspooled file many times in a job. Each flushed 'segment' can havethe tens of thousands of messages, and there could be thousands ofsegments. Total count of DISPLAY messages can be in the millionspretty quickly.

When the message queue segment is flushed, the amount of detail thatis set to be printed per message is also controlled by LOG(). Thatis specified by the 'Text' portion of LOG(). If all you want to seeis the message text itself, then specify LOG(n n *MSG). [Where 'n n'is the message level followed by severity that you want.]

IOW, you have a whole bunch of control and the control can beachieved at various levels. The control can be at a system defaultlevel; it can be for the set of jobs that use a particular jobdescription; it can be for an individual job that you submit withSBMJOB; or it can be done dynamically within the job itself viaCHGJOB. The CHGJOB command can also be run by you from acommand-line against your batch job as many times as you want tochange the attributes while your job runs.

Lots of choice and reasonably easy to exercise any choice. (The fullset of choices actually goes farther.) Of course, you can also shootyourself in the foot if you hit a loop that won't end and you'veoverridden the controls...

Tom Liotta