Explore topic-wise InterviewSolutions in .

The INDEX and the distributed free space. CI and CA splits upon UPDATES. Record LENGTH may be changed during the time of update. The records are ACCESSED by a particular Key in KSDS.

The index and the distributed free space. CI and CA splits upon updates. Record length may be changed during the time of update. The records are accessed by a particular Key in KSDS.

VSAM increases the disk SPACE requirements of systems. This is because VSAM offers certain capabilities LIKE PARTIAL self-reorganization to make things more EFFICIENT in data sets that can be modified.

VSAM increases the disk space requirements of systems. This is because VSAM offers certain capabilities like partial self-reorganization to make things more efficient in data sets that can be modified.

They are stored without respect to the contents of the RECORDS and in the ORDER in which they are INCLUDED in the FILE.

They are stored without respect to the contents of the records and in the order in which they are included in the file.

You can USE the LISTCAT COMMAND.

You can use the LISTCAT command.

Give (+1) as the generation number, give (new,catlg) for disp, give space PARAMETER, can give the dcb parameter if you WANT to OVERRIDE the dcb of the model DATASET.

Give (+1) as the generation number, give (new,catlg) for disp, give space parameter, can give the dcb parameter if you want to override the dcb of the model dataset.

base-file-name.GnnnnnV00 where NNNN= generation number (UPTO 255). nnnn will be 0000 for the 1st generation.

base-file-name.GnnnnnV00 where nnnn= generation number (upto 255). nnnn will be 0000 for the 1st generation.

It is not required, the DCB of the model DATASET can be OVERRIDDEN when you ALLOCATE new versions.

It is not required, the DCB of the model dataset can be overridden when you allocate new versions.

We can use the DEFINE GENERATIONDATAGROUP command. In the same IDCAMS step, ANOTHER DATASET must be defined whose DCB parameters are used when new generations of the GDG are created. This dataset is known as the model dataset. The DS name of this model dataset must be the same as that of the GDG, so use a disp of keep rather than CATLG and also specify space=(trk,0) 

We can use the DEFINE GENERATIONDATAGROUP command. In the same IDCAMS step, another dataset must be defined whose DCB parameters are used when new generations of the GDG are created. This dataset is known as the model dataset. The ds name of this model dataset must be the same as that of the GDG, so use a disp of keep rather than catlg and also specify space=(trk,0) 

In VSAM, Sequential(QSAM) FILES can be CREATED on TAPE while ESDS files cannot be created. Again, you can have ALTINDEX for an ESDS while no such FACILITY that exists for QSAM files.

In VSAM, Sequential(QSAM) files can be created on tape while ESDS files cannot be created. Again, you can have ALTINDEX for an ESDS while no such facility that exists for QSAM files.

For LOADING we can USE the REPRO COMMAND.

For loading we can use the REPRO command.

It INDICATES duplicate ALTERNATE key. It happens on both INPUT and OUTPUT operation.

It indicates duplicate alternate key. It happens on both input and output operation.

You can WRITE a DUMMY program that will just OPEN the file for OUTPUT and thereafter closes it.

You can write a dummy program that will just open the file for output and thereafter closes it.

A VSAM file that has never contained a record is treated as unavailable. ATTEMPTING to open for INPUT will fail. An EMPTY file can be opened for OUTPUT only. When you open for output, COBOL will WRITE a dummy record to the file & then delete it out.

A VSAM file that has never contained a record is treated as unavailable. Attempting to open for input will fail. An empty file can be opened for output only. When you open for output, COBOL will write a dummy record to the file & then delete it out.

 There are TWO WAYS to achieve that.Firstly by USING the REPRO command and SECONDLY by using COBOL program.

 There are two ways to achieve that.Firstly by using the REPRO command and secondly by using COBOL program.

We can fix it by the FOLLOWING. 

• By DEFINING new VSAM Dataset allocated with more space.
• By using IDCAMS to REPRO the old VSAM file to new VSAM Dataset.
• By using IDCAMS to ALTER / rename the old VSAM Dataset or set IDCAMS to DELETE the old VSAM Dataset.
• By using IDCAMS to ALTER / rename the new VSAM Dataset to the name of the original VSAM Dataset.

We can fix it by the following. 

DEFINE MODEL PARAMETER specifies WHETHER the MODEL parameter ALLOWS you to model your cluster by MODELLING it after an existing cluster.

DEFINE MODEL parameter specifies whether the MODEL parameter allows you to model your cluster by modelling it after an existing cluster.

SHAREOPTIONS PARAMETER specifies how the file may be shared between JOBS and between BATCH and CICS Environments.

SHAREOPTIONS parameter specifies how the file may be shared between jobs and between batch and CICS Environments.

They are INDEX, DEFINE CLUSTER and DATA.

They are INDEX, DEFINE CLUSTER and DATA.

• ALTER is used for modification of information for a catalog, alternate index, CLUSTER or path.
• BLDINDEX is used to BUILD the alternate index.
• DEFINE is used for ALTERNATEINDEX, CLUSTER or PATH.
• DELETE is used to remove the catalog entry for a catalog, cluster, alternate index or path.
• LISTCAT is for listing Information about the Dataset.
• PRINT is used to print the Dataset contents.
• REPRO is used to copy RECORDS from one file to another.

IDCAMS is the UTILITY, the ACCESS METHOD SERVICES utility.

IDCAMS is the utility, the access method services utility.

VSAM slot is a relative RECORD Dataset (RRDS) consists of a specified number of AREAS called slots. Each slot is identified by a relative record number (RRN) which INDICATES its relative position in the file.

VSAM slot is a relative record Dataset (RRDS) consists of a specified number of areas called slots. Each slot is identified by a relative record number (RRN) which indicates its relative position in the file.

They are end of file (10), duplicate Key (22), RECORD not found (23), Out of space condition is raised (28) ,VSAM logic error (90), open problem (92) and space problem (93).bIt is a COBOL II enhancement to VSAM batch processing expanding the FILE STATUS field.It is defined in WORKING - STORAGE as a six BYTE GROUP item with three two byte elements, the normal return code, the function code and the feedback code.

They are end of file (10), duplicate Key (22), record not found (23), Out of space condition is raised (28) ,VSAM logic error (90), open problem (92) and space problem (93).bIt is a COBOL II enhancement to VSAM batch processing expanding the FILE STATUS field.It is defined in WORKING - STORAGE as a six byte group item with three two byte elements, the normal return code, the function code and the feedback code.

Dynamic processing means ONE PROGRAM USES both sequential and random processing for a VSAM KSDS file. It is however RARELY used in VSAM.

Dynamic processing means one program uses both sequential and random processing for a VSAM KSDS file. It is however rarely used in VSAM.

In VSAM, the START command is USED to read other than the next VSAM RECORD. For this, A value must be MOVED into the RECORD KEY. HOWEVER, the KEY CLAUSE is optional, but it can be used to specify a relational operator.

In VSAM, the START command is used to read other than the next VSAM record. For this, A value must be moved into the RECORD KEY. However, the KEY clause is optional, but it can be used to specify a relational operator.

If there is a memory CRUNCH and there is not enough space in the Control Interval, VSAM PERFORMS a Control Interval SPLIT by moving some records to the FREE Control INTERVALS. If there isn't a free Control Interval,then VSAM performs a control area split by allocating a new control area and moving half of the Control Intervals to it.

If there is a memory crunch and there is not enough space in the Control Interval, VSAM performs a Control Interval split by moving some records to the free Control Intervals. If there isn't a free Control Interval,then VSAM performs a control area split by allocating a new control area and moving half of the Control Intervals to it.

It should be OPENED Input/Output MODE.

It should be opened Input/Output mode.

The FILE STATUS FIELD is used to IDENTIFY the field that VSAM uses to PROVIDE INFORMATION about each I/O Operation for the file.

The FILE STATUS field is used to identify the field that VSAM uses to provide information about each I/O Operation for the file.

The RECORD KEY in the SELECT clause IDENTIFIES the files PRIMARY Key as it will be made available to the PROGRAM.

The RECORD KEY in the SELECT clause identifies the files Primary Key as it will be made available to the program.

PRIMARY KEY values must always be UNIQUE however alternate Key values need not be unique all the TIME.

Primary Key values must always be unique however alternate Key values need not be unique all the time.

In ESDS the new RECORD is added at the END of last record. And no embedded free SPACE is allocated at the TIME of Dataset definition. In the case of RRDS the slots for the records are pre-allocated and so the CI and CA split is not possible.

In ESDS the new record is added at the end of last record. And no embedded free space is allocated at the time of Dataset definition. In the case of RRDS the slots for the records are pre-allocated and so the CI and CA split is not possible.

IDCAMS, also known as ACCESS METHOD Services, is used to perform the following tasks cited below.

• Createing a VSAM data set, VSAM alternate index, or catalog.
• Conversion of non-VSAM to VSAM data set.
• Listing a catalog entry for a data set, Dataset/catalog contents.
• Copy a Dataset or catalog.
• LOADING of a VSAM Dataset from VSAM records
• Renaming of VSAM data sets.

IDCAMS, also known as Access Method Services, is used to perform the following tasks cited below.

VSAM will INFORM COBOL program of the PROBLEM and TERMINATE the processing of the program.

VSAM will inform COBOL program of the problem and terminate the processing of the program.

The three POSSIBILITIES for ACCESS can be RANDOM, SEQUENTIAL or DYNAMIC.

The three possibilities for ACCESS can be RANDOM, SEQUENTIAL or DYNAMIC.

For a KSDS, the ORGANIZATION is INDEXED.

For a KSDS, the ORGANIZATION is INDEXED.

The base cluster in VSAM CONSISTS of the data COMPONENT as WELL as the index component that is REQUIRED for the primary index of a KSDS.

The base cluster in VSAM consists of the data component as well as the index component that is required for the primary index of a KSDS.

The UPGRADE set is the list of all AIXS that VSAM must be maintaining for a SPECIFIC base cluster, so that when data in the base cluster is modified or updated, the AIX files are ALSO updated.

The upgrade set is the list of all AIXs that VSAM must be maintaining for a specific base cluster, so that when data in the base cluster is modified or updated, the AIX files are also updated.

Below are the 3 types of VSAM files.

1. ESDS (Entry sequenced dataset). DB2 uses a SPECIAL type of ESDS.
2. RRDS (RELATIVE record dataset). Records are accessed using a relative number.
3. KSDS (Key sequenced dataset) is the most common type encountered. The record SEQUENCE is DETERMINED by a unique key FIELD.

Below are the 3 types of VSAM files.

There are 2 data buffers by DEFAULT for ESDS. For KSDS it allots 2 data buffers and 1 index buffers. Each BUFFER is about 4k.

There are 2 data buffers by default for ESDS. For KSDS it allots 2 data buffers and 1 index buffers. Each buffer is about 4k.

With the HELP of the IDCAMS UTILITY with the REPRO OPTION.

With the help of the IDCAMS utility with the REPRO option.

You use the IDCAMS UTILITY with the DEFINE CLUSTER OPTION.

You use the IDCAMS utility with the DEFINE CLUSTER option.

Every AMS command issues a condition code. If multiple COMMANDS are being executed successively, there might be a requirement to execute or bypass certain commands on the Success or FAILURE of a previous command. The normal condition CODES returned by AMS commands are :

0 - The function was executed successfully.
4 - A problem was encountered while executing the function, WARNING.
8 - The requested function was executed, but MAJOR specifies were unavoidably bypassed,ERROR.
12 - The requested command could not be performed because of a logical error, SEVERE.
16 - A severe error occurred causing the remainder of the command stream to be bypassed., FATAL.

Every AMS command issues a condition code. If multiple commands are being executed successively, there might be a requirement to execute or bypass certain commands on the Success or failure of a previous command. The normal condition codes returned by AMS commands are :

0 - The function was executed successfully.
4 - A problem was encountered while executing the function, WARNING.
8 - The requested function was executed, but major specifies were unavoidably bypassed,ERROR.
12 - The requested command could not be performed because of a logical error, SEVERE.
16 - A severe error occurred causing the remainder of the command stream to be bypassed., FATAL.

GDG MEANS GENERATION DATA GROUP.

GDG means Generation Data Group.

We cannot DELETE, you have to give a SEPARATE DELETE command in the VSAM cluster.

We cannot delete, you have to give a separate DELETE command in the VSAM cluster.

The delete operation is not supported. Delete operation is not POSSIBLE in VSAM ESDS. Yes, rewrite operation is possible in an ESDS.

The delete operation is not supported. Delete operation is not possible in VSAM ESDS. Yes, rewrite operation is possible in an ESDS.

i) Skip and Count :
Syntax:
SKIP(2)
COUNT(4)

In this case, the first two records are skipped and the next four records are printed. The DEFAULT for SKIP is 0, and for COUNT will be printing records from BEGINNING to end.

ii) FromKey and ToKey :
PRINT -
INDATASET (CUSTOMER.KSDS.CLUSTER) -
FROMKEY (111111) -
TOKEY (444444)
Will print all records with Key VALUE ranging from 111111 to 444444.
iii) FROMADDRESS and TOADDRESS.
iv) FROMNUMBER and TONUMBER.

i) Skip and Count :
Syntax:
SKIP(2)
COUNT(4)

In this case, the first two records are skipped and the next four records are printed. The default for SKIP is 0, and for COUNT will be printing records from beginning to end.

ii) FromKey and ToKey :
PRINT -
INDATASET (CUSTOMER.KSDS.CLUSTER) -
FROMKEY (111111) -
TOKEY (444444)
Will print all records with Key value ranging from 111111 to 444444.
iii) FROMADDRESS and TOADDRESS.
iv) FROMNUMBER and TONUMBER.

It is used to define the cross-region and cross-system SHARING capabilities of the DataSet. SYNTAX is SHR (CRvalue CSvalue)

1. means multiple read OR single write (read INTEGRITY).
2. means multiple read AND single write (Write integrity).
3. means Multiple read AND multiple write.
4. is same as 3, which refreshes the buffer with EVERY random access. Default is SHR(1 3).

It is used to define the cross-region and cross-system sharing capabilities of the DataSet. Syntax is SHR (CRvalue CSvalue)

YES it slower because the alternate Key WOULD FIRST locate the PRIMARY Key, which in turn locates the actual record. It requires twice the number of I/Os.

Yes it slower because the alternate Key would first locate the primary Key, which in turn locates the actual record. It requires twice the number of I/Os.

The parameters RECOVERY (default) and SPEED are mutually exclusive. Recovery is used to pre-format the control areas during the initial DataSet load, if the JOB fails, you can restart but you MUST have a recovery routine already written to restart the job. SPEED does not pre-format the CAs. It is advisable that you specify SPEED to speed up your initial data load.

The parameters RECOVERY (default) and SPEED are mutually exclusive. Recovery is used to pre-format the control areas during the initial DataSet load, if the job fails, you can restart but you must have a recovery routine already written to restart the job. SPEED does not pre-format the CAs. It is advisable that you specify SPEED to speed up your initial data load.

Whenever a new CLUSTER is created using IDCAMS, the cluster will be empty. By the use of REPRO command, we are ABLE to load records into the cluster. REPRO is used to:

• Copy Datasets (VSAM or NON-VSAM), copy catalogs.
• Conversion of SEQUENTIAL and index sequential Datasets to VSAM format.
• Backup VSAM catalog
• Conversion of VSAM and Index sequential Datasets to sequential format
• Read a backup copy of VSAM catalogs.

Whenever a new cluster is created using IDCAMS, the cluster will be empty. By the use of REPRO command, we are able to load records into the cluster. REPRO is used to:

LIBRARIES are of three types: System

1. Libraries:- such as SYS1.LINKLIB Private 
2. Libraries:- Specified in a JOBLIB or STEPLIB DD STATEMENTS.
3. Temporary Libraries:- CREATED in a previous step of the Job.

Libraries are of three types: System