Job Management

proces-sing required for communication between an operator and the control program. Major components of job management are the job scheduler, which introduces each job step to the system (job processing), and the communications and master scheduler tasks, which handle all operator-system communica-tion (command processing).

JOB SCHEDULER FUNCTIONS

The job scheduler includes three programs:

the reader/interpreter, the initiator/

terminator, and the system output writer.

The functions of the reader/interpreter are similar to the MVT reader; additional

information can be found in IBM System/360 Operating System: MVT Job Management, Pro-gram Logic Manual, Form Y28-6660.

After all control statements for a job have been processed, all initiators that are waiting for that job class are posted and the initiator residing in the highest priority partition is given control. The MFT initiator is described in the Job Man-agement section of this publication; for information on allocation and termination, refer to IBM System/360 Operating System:

MVT Job Management, Program Logic Manual, Form Y28-6660.

When the job step has been executed, control is returned to the initiator/

terminator which performs data set disposi-tions and releases input/output (I/O) resources. If the entire job is to be ter-minated, the terminator enqueues all data sets on the appropriate system output (SYS-OUT) queues.

When the system output writer receives control, i t dequeues a job from an output queue, and transcribes the data sets to the user-specified output device. (see IBM System/360 Operating System: MVT Job Man-agement, Program LOgic Manual, Form

Y28-6660, for further information on the system output writer.)

COMMUNICATIONS TASK FUNCTIONS

The routines of the communications task process the following types of communica-tion between the operator and the system:

• Operator commands, entered through a console.

• Write-to-operator (WTO> and write-to-operator with reply (WTOR) macro in-structions.

• Interruptions caused when the INTERRUPT key is pressed, to switch functions from the primary console/master console to its alternate console.

• If the system has ^~ultipleConsole Sup-port, the communications task processes the delete operator message (DCM) macro instruction and provides buffer manage-ment for all console devices.

MASTER SCHEDULER TASK FUNCTICNS

The master scheduler task consists of SVC 34 and the master scheduler resident com-mand processor routines. The SVC 34 mand scheduler routines process all com-mands initially. The job queue manipula-tion and partimanipula-tion definimanipula-tions, which are not fully processed by SVC 34, are passed to the master scheduler resident command processor. Table 1 lists the commands used in MFT and indicates the routine which responds to the commands after initial processing.

Table 1. Responders to Commands After Initial Processing

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Figure 12 shows the major components of job management and the general flow of control.

Control is passed to job management Iwhenever the supervisor finds that there

are no program request blocks in the re-quest block queue. This can occur for two reasons: either the initial program load-ing (IPL) procedure has just been

com-pleted, or a job step has just been executed.

Entry to Job Management Following Initial Program Loading

Following IPL" certain actions must be taken by the operator before job processing can begin. Therefore, control passes to the communications task which issues a mes-sage to the operator instructing him to

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See Table 1.

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.Figure 12. Job Management Data Flow

enter commands, or to redefine the system.

If he chooses to redefine the system, con-trol passes to the master scheduler task to handle the redefinitions. If the system is not to be redefined, the initialization commands (a SET command, a START reader command, a START writer command, and a START INIT command) are issued (either automatically by the master scheduler task or by the operator performing the IPL), and job processing begins.

Entry to Job Management FOllowing Step Execution

Following step execution, control is passed to the step termination routine of the initiator/terminator. If no further job steps are to be processed, control is also

passed to the job termination routine of the initiator /termina tor. Both routines are described in the topic

·Initiator/~erminator."

MF'I job management is similar in many respects to MVT job management. However, certain major differences in logic exist.

~hese differences are described in two major topics. nCommand Processing"

includes the communications task and master scheduler task. "Job Processing" includes:

• Queue Management.

• Reader/Interpreter.

• Initiator/Terminator.

• system output writer.

• System task control.

• System restart.

References to IEM System/360 Operating module descriptions, and MFT flowcharts are included in the appendixes.

Dans le document Program Logic (Page 39-42)

Job Management

Job Management

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