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Few Useful FAQs/Interview Questions for Mainframe Beginers :

1. How to reconnect to Mainframes session when system says User already login ?
In Login Page check the Reconnect option with ‘S’ and then logon .. it will reconnect to the mainframe session

2. What is the basic use of directory blocks while creating pds ?
Directory blocks work like an index to the PDS and contain the member names of what is stored in the PDS. A directory block can hold approximately 6 member names so a PDS with 2 directory blocks can hold approximately 12 members and a PDS with 3 directory blocks can hold about 18 members

3.How to find How many members dose PDS has without opening it?
Open member in 3.4 optin and put ‘I’ to see the above information.

4.What is RESTART Parameter in JCL ?
RESTART Parameter is used to restart a job from specified/abended step manually. Below step shows how to start from step2 by skipping step1.

Eg: //Job1 Job Class=A, Restart = step2

5.How do you edit /resubmit a job which is available in spool ?
Use commands SJ or SE across (under column NP) the job in spool, and job will open in edit mode. Then sub the job. The changes made at this place are not reflected in actual job

6. How to open new session and swap between the screens ??
Use START command in command line to open new session or Put List Command line and use F9 Key .. u get a pop window start new session option there

Use F9 key to swap between the session.

7. I have opend 10 screens. How to got to 9th screen ?
Put 9 on command line and press key F9 .. it will take u to 9 the screen. OR

Other way is to name your screen by some name.
a. Use the command screenname SA and enter
b. To get back to this screen, use SA in command line and press F9

8.Can a input/output file can have a record length of more than 80 ?
Yes, an input and output file can have file record length of more than or less than 80.
Only report file has a fixed length of 133 bytes of which 1 byte is used for line control by system

9.What is the length of Report ?
Record length of file should be 133 only, of which 132 bytes is used for data to be printed and one byte is used by printer for line control information

Eg : Example for Report defination
01 FD Report-rec
05 Rep-cntl PIc X(01) -- used by systen for line control info.
05 Rep-Rec PIC X(132).

10. What are Redifines ??
Redefines is used to share the same memory by different variable for reusability. This way we can redefine Numeic as Alphanumeric and vice versa... This is basic advantage of redefines.
Eg :
05 Ws-Alpha Pic X(40)
05 Ws-Num Redefine Ws-Alpha PIC 9(40)


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