If you define in the PCEDEF initialization statement that your MAS is to have more than one converter processor (CNVTNUM=2 or CNVTNUM > 2), then concurrent JES2 converter job processing can take place. However, this concurrent processing does affect the sequence of job execution. Two or more jobs with the same class and the same priority can be in conversion processing at the same time. Whichever job finishes conversion first is then queued for execution first, regardless of the order in which the job was submitted. You need to consider the following implications when setting up your system with CNVTNUM=2 or CNVTNUM>2:

• JES2 conversion processing occurs in different ways depending on whether the conversion processor represents an "even" (2,4,6, and so on.) or "odd" conversion processor (3,5,7, and so on.). As an example, for CNVTNUM=5, you define "3" odd conversion processors (1,3,5) and "2" even conversion processors (2,4). An even-numbered processor continually processes jobs through JES2 conversion and does not wait. An odd-numbered processor waits for a job's resources to become available.

  Odd-Numbered Conversion Processing

  Odd-numbered conversion processing waits for the resources to be available. When the resources become available, conversion continues.

  There are two primary conditions that affect JES2 conversion processing:

  1. JCLLIB data sets need to be recalled for a job to proceed.

     Conversion processing waits for the recall of the JCLLIB data sets to occur then proceeds with the conversion.

  2. The JCLLIB data set is controlled (typically by an exclusive ENQ) by another job.

     Conversion processing waits for the exclusive control to be released.

  Even-Numbered Conversion Processing

  Even-numbered conversion processing does not wait; it requeues jobs that need resources so that they are processed by the odd-number conversion processor. Jobs that have all their resources are converted immediately.

  Note: To have at least one converter PCE free to process jobs at all times, you need to define a minimum of "2" converter PCEs in the PCEDEF initialization statement.
• If you need one job selected before another and you accept the "default" number of conversion processors or define more, you can control the sequence of job execution through the following types of procedures:
  • Delay the selection of the second job by coding TYPRUN on the JOB statement for that job
  • Specify a job class for the second job that will force the job into hold status
  • In a shared spool environment, assign a specific system affinity to each reader in your system through the RDR(nn) initialization statement, $T RDRnn operator command, or on the /*JOBPARM statement for the job.
  • Add an additional step to the first job to submit the second job to the internal reader. As a result, the first job must complete before the second job can run.
  • You can affect the status of jobs entering the system, and the order in which JES2 selects jobs for processing by using the following JES2 installation exits:
    • Exit 2 or 52 for JOB statement scan
    • Exit 20 or 50 for end-of-job-input processing
    • Exit 51 for end of phase processing
    • Exit 6 or Exit 60 for converter/interpreter text
    • Exit 14 for job queue work selection (before a job is selected)
    • Exit 49 for job queue work selection (after a job is selected by QGET)
    • Exit 22 for processing of TSO/E STATUS and CANCEL commands
    • Exit 44 for determining whether a job waits for migrated resources

    z/OS JES2 Installation Exits gives details about using these exits.