Batch processing is a powerful feature in Control Language (CL) that allows you to execute a series of commands or programs without manual intervention. This is particularly useful for tasks that need to be performed regularly or require significant computational resources. In this section, we will cover the basics of batch processing, how to create and manage batch jobs, and practical examples to help you understand and implement batch processing in your CL programs.

1. Batch Job: A job that is submitted to the system to be processed at a later time or under specific conditions.
2. Job Queue: A queue where batch jobs are placed before they are executed.
3. Job Description: A set of attributes that define how a job should be processed.
4. Job Scheduler: A system component that manages the execution of batch jobs based on predefined criteria.

To create a batch job, you need to define the job's attributes and submit it to a job queue. Here is a step-by-step guide:

A job description specifies the attributes of the job, such as the job name, user profile, and job queue. You can create a job description using the CRTJOBD (Create Job Description) command.

Write a CL program that contains the commands you want to execute as part of the batch job. Save this program in a source physical file.

Use the SBMJOB (Submit Job) command to submit the CL program to the job queue.

Once a batch job is submitted, you can manage it using various CL commands:

• WRKJOB: Work with a specific job.
• WRKACTJOB: Work with active jobs.
• WRKSBMJOB: Work with submitted jobs.
• ENDJOB: End a job.
• HLDJOB: Hold a job.
• RLSJOB: Release a held job.

You can monitor the status of a batch job using the WRKSBMJOB command.

This command displays a list of submitted jobs, allowing you to check their status, hold, release, or end them as needed.

Let's create a practical example where we automate a daily backup process using batch processing.

This command schedules the DAILYBACKUP job to run at 11:00 PM every day.

1. Create a job description named MYJOBD with the job queue QBATCH and user MYUSER.
2. Write a CL program that sends a message "Hello, Batch World!".
3. Submit the CL program as a batch job named HELLOBATCH.

1. Create the job description:

   CRTJOBD JOBD(MYJOBD) JOBQ(QBATCH) USER(MYUSER) TEXT('My Job Description')
   

2. Write the CL program:

   PGM
       DCL VAR(&MSG) TYPE(*CHAR) LEN(50)
       CHGVAR VAR(&MSG) VALUE('Hello, Batch World!')
       SNDPGMMSG MSG(&MSG)
   ENDPGM
   

3. Submit the batch job:

   SBMJOB CMD(CALL PGM(MYLIB/HELLOCLPGM)) JOB(HELLOBATCH) JOBD(MYJOBD)
   

1. Submit a batch job that runs a CL program to create a backup of a library.
2. Use the WRKSBMJOB command to monitor the job.
3. Hold the job using the HLDJOB command.
4. Release the job using the RLSJOB command.

1. Submit the batch job:

   SBMJOB CMD(CALL PGM(MYLIB/BACKUPCLPGM)) JOB(BACKUPJOB) JOBD(BACKUPJOBD)
   

2. Monitor the job:

   WRKSBMJOB JOB(BACKUPJOB)
   

3. Hold the job:

   HLDJOB JOB(BACKUPJOB)
   

4. Release the job:

   RLSJOB JOB(BACKUPJOB)
   

In this section, we covered the basics of batch processing in CL, including creating and managing batch jobs. We also provided practical examples and exercises to help you understand and implement batch processing in your CL programs. Batch processing is a powerful tool for automating repetitive tasks and optimizing system performance. In the next section, we will explore data integration techniques to further enhance your CL programming skills.