Job stream
| Industry | Computer hardware, software, and mainframe systems |
|---|---|
| Founded | June 16, 1911 |
| Headquarters | Armonk, New York , United States |
In a non-interactive computing environment, particularly within IBM mainframe systems, a job stream or simply job denotes a series of job control language (JCL) commands along with associated data (referred to as instream data) that collectively represent a single operational task for the operating system. Traditionally, the word job implies a one-time operation, distinct from a batch, which involves repeatedly performing identical procedures on multiple inputs. Nevertheless, since non-interactive processing is commonly identified as "batch processing", an individual batch processing unit is also called a job or batch job. Executing a job entails running one or more programs, each termed a job step or simply a step. These steps proceed in sequence, often relying on the outcomes of preceding steps, especially within batch workflows.
The phrase "job stream" is mainly associated with mainframe environments; within the IBM z/OS operating system, a job commences with a // JOB statement and concludes upon encountering the next // JOB or // delimiter. Each individual step contains a // EXEC command that identifies the program to run, accompanied by several // DD statements that specify the files and devices involved.
Example
An example of a job stream designed for printing payroll checks might include these sequential steps on a batch of input data:
- Retrieve employee identification numbers and hours worked; perform data validation.
- Compute wages and deductions; update employee master files; prepare data for subsequent steps.
- Produce payroll checks based on the generated information.
- Adjust bank account balances to reflect the issued payroll checks.
The success of each step depends on the completion of the previous one. For instance, if input data fails validation, the job may be halted to allow corrections before re-execution. When no errors are detected, the job proceeds to completion without requiring manual intervention.