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VB (Variable Blocked) file:
There are two types of control information in a VB file-
There might be several records in one physical block. Each variable length record has a RECORD DESCRIPTOR WORD(RDW).
RDW is of 4 bytes. The first 2 bytes store the length of the record. Each block has a BLOCK DESCRIPTOR WORD(BDW) at the beginning of the block. The BDW is of 4 bytes. The first 2 bytes contain the length of the block.
The representation of a VB block file is below-
BDWRDWRECORDRDWRECORDRDWRECORD
That is why when the logical record length of a Variable blocked file is 80 , it is 4 bytes RDW and 76 bytes data.
In a VB file, BDW and RDW manage block and record lengths. Each RDW is 4 bytes, with 2 bytes for record length. BDW is also 4 bytes, with 2 bytes for block length. For an 80-byte logical record, 4 bytes are RDW, and 76 bytes are data.
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Distinction between CHAR and VARCHAR data types -
CHAR data type has a predetermined maximum length, while VARCHAR data type is a varying length character string.
So, it means, Char will always have the same leng...
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Do you know what DBRM is?
DBRM is Database Request Module and is a component inside DB2, it is created after the pre-compilation of COBOL-DB2 program. This is a module that consists of SQL source statements that get ex...
What is a SUBSCRIPT in Mainframe?
Subscript:
A subscript is an integer value that indicates the position of an element in an Array(table). It can be defined in working-storage section with PIC S9(4) COMP. It's an integer that indicates...
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What is DCLGEN in DB2?
DCLGEN (Declarations generator) are used in the COBOL-DB2 programs that we write. The program should declare the tables and views that it accesses. DCLGEN produces these DECLARE statements so tha...
