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Q1)    What is the physical nature of a database called?

A1)     DBD

Q2)    Is it necessary that all the segments in a Dl/i database have key fields ?

A2)     It is not necessary that all the segments in the database should have key field, expect for the database.

Q3)    How man key fields and search fields can a segment have?

A3)     One key field and as many search fields in the segment can be declared.

Q4)    Is it necessary that the key field in a Dl/I database be unique?

A4)     No, it is no necessary.

Q5)    What is a key field in an IMS database?

A5)     A Field that DL/I uses to maintain the segments in the ascending order is called the key field

Q6)    What is a database record?

A6)     A single occurrence of the root along with all its dependents is called the database record.

Q7)    What is a Hierarchy path?

A7)   A line that starts at the root and passes thru the inter mediate levels in the hierarchy and ends at the a segment at the bottom of the hierarchy is called the Hierarchy path.

Q8)    What is a Root?

A8)     The segment at the top of the Hierarchy, which is not a child to a segment is called the Root.

Q9)    What are Twins?

A9)     Occurrences of all the segment types under a single parent segment occurrence is called a Twin.

Q10)   Define the terms Parent & Child.

A10) Parent-Any segment that has one or more segments directly below it is a Parent. Child-Any segment that has segment directly above it is called the Child.

Q11)   What is the limitation on the no. of levels in a DL/I database?

A11)   You can have 15 levels in a DL/I database

Q12)   How many sgment types can u have in a DL/I database?

A12)   A Dl/I database can have 255 segment types

Q13)   What is a Segment type?

A13)   Loosely speaking a segment type is a segment in a Dl/I hierarchy chart.

Q14)   What is a segment?

A14)   A segment is the smallest unit of information that Dl/I uses when working with information in the database

Q15)   What is Hierarchy Chart?

A15) A Hierarchy chart is a pictorial representation of the total of a DL/I database starting from the root, giving all the parent child relationships that exist within the database

Q16)   what are the control blocks in IMS ?

A16)   There are two control block.1.dbd(database descriptor)2.psb       (program specification block)

Q17)   which is the first statement in COBOL-IMS programs?

A17)   Entry statement is the first statement after procedure division i.e. ENTRY ‘DLICBL’ USING …..

Q18)   What is the return code you get after a successful IMS call?

A18)   Spaces.

Q19)   Define DBD?

A19) DBD : Database Descriptor. IMS Controls the Structure of DB and access to the DB via DBD. The DBD contains information like, Segment types, their location in hierarchy and Sequence keys.

Q20)   How can we distinguish between an online and batch program in IMS environment?

A20) By seeing the IO-PCB in the application program.

Q21)   Which is the DL/I function used in CICS-IMS program?

A21)   PCB(PROGRAM COMMUNICATION BLOCK)

Q22)   What is IMS?

A22)   INFORMATION MANAGEMENT SYSTEM

Q23)   How does one reorg an HDAM IMS database when changing RAPS (Root Anchor Points)?

A23) Unload data using current DBD. 2. Delete/define the underlying VSAM dataset(s). 3. Re-load data using newly-defined DBD with new RAPs. 4. Re-build any secondary indexes.

Q24)   What do you know about DBD gen?

A24) used to generate DBDs.   The statements in DBDGEN process are PRINT NOGEN, DBD, DATASET, SEGM, FIELD, DBDGEN, FINISH, END

Q25)   What are common DLI functions?

A25) GU,GN,GNP,GHU,GHN,REPL,ISRT,DLET…

Q26)   What are common status codes that you come across?

A26) GE,GB,GD,GK,GP,AI,AB,AC,AK,AJ,AM,AU,DJ,II,IX,QC,QD,H…

GE – segment not found

GB – end of database

Q27)   What are the command codes and their purposes?

A27)   Command codes extends the function of a SSA call. It simplifies programming and it improves performance.

*C – Concatenated key,  D-path call, F- first occurrence, L- last occurrence,

N- path call ignore , P-set parentage.

Q28)   What are the parameters used in CBLTDLI call?

A28)   Function code, PCB mask, Segment I/O Area & SSA(s).

Q29)   What are qualified and unqualified SSA’s.

A29) A Qualified SSA contains Key field as well as search field and parenthesis An unqualified SSA does not contain key field and parenthesis

Q30)   What do you know about MFS?

A30) Message Format service , Used to format messages that will be transmitted to and from display screens.

Q31)   What for procopt is used? List some of them?

A31) Procopt parameter specifies PROCESSING OPTIONS that define the type of processing that can be performed on a segment. ex: K, G, L, LS, A ,AS, I, IS.

procopt=k—means , the segment is key sensitive

procopt=g- the segment is data sensitive (like read only)

L- Load mode , means we can load data base from scratch

A- Get, Insert, Delete, Replace- means it allows the program to issue  all  those calls

I-insert mode.  That means only insert calls with insert mode can be issued

Q32)   What is multi positioning ?

A32) Multi positioning is an option  where by IMS maintains a separate position on each hierarchical path. when more than one PCBs refer to the same DBD , it is called Multi positioning.

Q33)   What is secondary indexing?

A33) Secondary indexing is a feature which allows the program to sequentially retrieve segments or search for segments in a sequence other than key sequence.

Q34)   How many PCB’s can be coded within a PSB?

A34)   As many(more than one)

Q35)   What is PSB,PCB & ACB?

A35) PSB(Program specification block): Informs about how a specific program is to be access one or more IMS DB. It  consists of PCB.

PCB (Prg Communication Block): Information to which segment in DB can be accessed, what the program is allowed to do with those segment and how the DB is to be accessed.

ACB(Access Control Block):   are generated by IMS as an expansion of information contained in the PSB in order  to speed up the access to the applicable DBD’s.

 

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