JCL Interview Questions and Answers - DoAnswers.com

JCL (job control language) is a language for describing jobs (units of work) to the MVS, OS/390, and VSE operating systems, which run on IBM's S/390 large server (mainframe) computers. These operating systems allocate their time and space resources among the total number of jobs that have been started in the computer. Jobs in turn break down into job steps. All the statements required to run a particular program constitute a job step. Jobs are background (sometimes called batch) units of work that run without requiring user interaction (for example, print jobs). In addition, the operating system manages interactive (foreground) user requests that initiate units of work. In general, foreground work is given priority over background work.

JCL Interviews are getting tough these days as the technology grows faster. To get through the JCL interview one needs to update him/herself in a regular manner. Having said that, just before the interview, it is very important to have a quick glance of the reputed JCL questions and answers to make yourself comfortable during the interview process. This is where DoAnswers.com helps you in renewing yourself on JCL and various other technologies interview preparation.

31. Describe the JOB statement, its meaning, syntax and significant keywords?

The JOB statement is the first in a JCL stream. Its format is // jobname, keyword JOB, accounting information in brackets and keywords, MSGCLASS, MSGLEVEL, NOTIFIY, CLASS, etc.

1.of course. object orientation is a dicipline of programming at the source level. by the time it executes the machine instructions concepts like objects are long gone. 2.cobol 2002 is based on object oriented concepts and is the latest version of it. i guess mainframes with oo will soon be launched as the heart of it ie cobol is already ready with oo. 3.there is a language called cool which is a cobol object oriented language which is supported by mainframe. there are some companies which are already using cool from past 1980's. thanks 4.aion tool used in mainframes ,it's an expert system tool uses object oriented concepts in depth.

33. doesn't exist, the system changes mod to new unless the vol parameter request specific volume. when vol is coded, the stem

expects to find data set on the specified volume and terminates the step if it cannot find it. mod is the usual way of extended data sets in to several direct-access volumes.

datasets can be grouped in a dd statement one after another, eg. in a joblib statement where the load module can exist in one of many datasets. concatenation is also used to append files in the jcl for a single ddname. the order of appending will be from top file to bottom file. and the order of the records concatenated, stays still. merging files differ from concatenation, in a way that it will also sort after appending. when you specify multiple dataset to be concatenated in joblib or steplib, the library with largest blocksize will be picked first.

Datasets can be grouped in a DD statement one after another, eg. in a JOBLIB statement where the load module can exist in one of many datasets.

Datasets are concatenated by writing a normal DD statement for the first dataset and then adding a DD statement without a DDNAME for each dataset to be concatenated in the order they are to be read. The following is an example of three datasets concatenated: //YEARDAT DD DSN=JAN.DATA,DISP=SHR // DD DSN=FEB.DATA,DISP=SHR // DD DSN=MAR.DATA,DISP=SHR

Generation Data Groups are concatenated by specifying each dataset name and the generation number for all generations of the generation data group. Otherwise to have all generations of a generation data group, omit the generation number. The DD statement will refer to all generations. The result is the same as if all individual datasets were concatenated. If generations are not on the same volume, this will not work.