JCL Interview questions

JCL is an acronym popular for Job Control Language, a command language principally owned by Multiple Virtual Storage (MVS). It is utilized by a wide variety of operating systems by the IBM Mainframe electronic devices such as laptops and computers.

Some of the advantages of using JCL language include:

• It can be used for deleting and creating a wide range of data sets, VSAM clusters and GDG’s.
• can be used for comparing files with different PDS members
• It can be used for merging as well as sorting various data files
• It can also be used for executing and compiling programs

The different components of the JCL statement include:

• Name field
• Operation field
• Comments

The difference between run mode and addressing mode in JCL language are:

The following include the purpose of using the DISP Parameter:

• It is used for postulating the character of the data set
• The status of the data can be specified at different stages such as at the beginning of the step or after the successful completion of the step or even after the abnormal execution of the respective step

There are a set of predefined rules followed while naming the steps in a job. These rules include the following:

• The steps should be purely meaningful, real and unique. This rule is crucial as different systems identify the job based on this rule.
• The step name must be coded only after the symbol “//” with no space in between
• The step name should follow after the job statement has been completely declared
• A particular job can have many steps, however, all the names must be different
• The step name should be followed after a blank space
• The step name can contain all alphabets, all numbers and the following symbols #, @ and $
• The first character of the step name should be a symbol or an alphabet

A terminology "keyword" in various JCL statement might appear in different places and can be seen by its name, for example, MSGCLASS inside the various JOB statements. The inverse of the terminology "keyword" is known as positional words, where its significance relies upon the circumstance in the announcement. For example, in the keyword of DISP the = (NEW. CATLG, DELETE) whose importance relies upon the primary, secondary and tertiary position of terms.

One of the following methodologies can be adapted to transfer data to a program that is coded using the EXEC statement:

• With the help of utilizing of the PARM in the JCL and coding using the receiving variable in the linkage segment of COBOL. For this situation, the "Technique DIVISION USING" explanation will be utilized.
• By transferring information as instream in the JCL and coding an ACCEPT proclamation in the COBOL.
• By transferring the required information in a level document and coding record descriptor and so forth in the COBOL program.

The following is the hierarchical level of JCL:

• Name
• Fields
• Operations
• Operands
• Parameters
• 1-positional
• 2-keyword
• Comments if any

Various parameters used in creating GDG include the following:

• Name: This is the name of the GDG that will be made.
• Limit(n): The maximum number of ages that exists at a given point in time.
• Void: Deletes every single older established generation once it has achieved the maximum of its potential.
• NoEmpty: Removes every single older established generation once it has achieved the maximum of its potential.
• Scratch: Removes various generations that are totally after the cancellation of the information set.
• NoScratch: Uncataloged dataset, when the dataset is expelled.

A job time – out failure can happen when the program takes additional time than the prescribed limit for the particular specified class, this is commonly known as the S322 abend. This failure is experienced when there are some circling errors in the program and it does not achieve completion.

On the off chance that the information handled in the program is really gigantic and needs additional time than the specific class, at that point the TIME parameter can be coded as TIME = 1440 to land vast time until job finishing.

JOBLIB and STEPLIB are utilized to indicate the library to be sought before the default framework libraries so as to find a program to be executed by the progression of steps. STEPLIB is relevant just to the specific advance while JOBLIB is pertinent to all means in the activity.

NOTCAT 2 - GS exists as the MVS message that shows a copy of the existing catalog section For example on the off chance that you as of now have a dataset with DSN = 'xxxx.yyyy' and u attempt to make one with disp new, catlg, then you ought to get this faulty notification.

The opening and composing of the program would cause an experience of error towards the finish of the progression of the framework that can try to place it inside the framework list. Now since a section as of now subsets the catlg ought to come up short and notify this kind of message. Thus one can try to fix the issue by erasing the primary set of information and set off to the length of possibilities where the latest dataset is present (this data is in the msglog of the activity) and thus finally classify it.

In view of the time length and the quantity of assets prerequisite by the activity, organizations appoint diverse occupation courses. These can be envisioned as discrete schedulers utilized by the OS to get the employment. Setting the jobs within the correct scheduler will help in the simple accomplishment of the employment.

A few organizations have distinctive classes for employment in various test and generation condition. Legitimate qualities for CLASS constraints include alphabetic characters (a to z) in addition to numerals (0 to 9 - of length 1). Succeeding is an example of the typical linguistic structure − CLASS=0 to 9 | beginning to end.

Amongst the numerous, some of the statements that are not permitted in various procedures include the following:

• DD * or Data statements
• JES2 or JES3 control statements
• JOB, Delimiter or Null statements
• JOBLIB or JOBCAT DD statements