COBOL_Training_Class-9.ppsx

7/27/2019 COBOL_Training_Class-9.ppsx

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IBM MAINFRAMES

COBOL Training Class-9



Usage Clause

The data can be stored in different format’s by using USAGE

CLAUSE the programmer can defined the data storage and

format of a particular field at the time of declaration.

Possible values for USAGE CAUSE !isplay "default# Character format.

Computation $ C%&P

C%&P'( $ C%&P')

C%&P'* "%+# Pac,ed !ecimal

-hen e use display usage clause each character ill store in

a one byte



Refreshing Basics

Nibble: 4 Bits Is One Nibble.

Byte: 8 Bits Is One Byte.

Half Word: ! Bits Or " Bytes Is One Half Word.

#$ll Word: %" Bits Or 4 Bytes Is One #$ll Word.

&o$ble Word: !4 Bits Or 8 Bytes Is One &o$ble Word.



Comu!a!ion COM"

/n CO'( data items the data stored is represented in

Binary format.

P/C clause can contain S and ) only. "0 1%T A%-E!#

* WS+&A,AI,E' (IC S)-* CO'(. The memory allocation ill be as follos

S2"3(# 4 S2"35# 6alf ord 7inary.

S2"38# 4 S2"32# 9ull ord 7inary.

S2"(3# ' S2"(:# !ouble ord 7inary.

&ost significant bit is %1 if the number is negative.



Comu!a!ion COM"-# an$ COM"-%

C%&P'( is used for Single ord floating point item. This

ill occupy 5 bytes

C%&P') is used for declaring !ouble ord floating'pointitem. This ill occupy : bytes

P/C Clause should not be specified for both C%&P'( and

C%&P').



Comu!a!ion COM"-&

C%&P'* is used to store the data in Pac,ed !ecimal$

he;adecimal representation.

/n this To digits are stored in each byte.

P/C clause can contain S/ 0 and ).

ast nibble is for sign. "9 for unsigned positive< C for signed

positive and ! for signed negative# < east significant bit is %1 if

the number is negative

&emory calculation is done ith the 9ormula – S2"1# C%&P'*

#or E1en number "1$)# = ( #O2 O&& number "1=(#$).



'ifference (e!)een COM" * COM"-&

(. Comp is a binary usage< hile comp'* indicates 3a5ed

dei6al.

). /n comp only S and 2 are alloed< hile in C%&P'* S / )

and 0 are alloed

*. 9or 7i7er bo$ndaries comp is better here as comp'* for

lo9er bo$ndaries

5. 9or comp the ma;imum bytes can be 8 bytes< here as for

comp'* it ould be bytes>8. 9or comp the sign bit is stored at 'ost Sinifiant Bit here

as for comp'* the sign is stored at Least Sinifiant Bit.



ON SI+E ERROR

%1 S/?E E++%+ clause is coded to trap si@e errors in arithmetic

operation.

E;ample

A!! A T% 7 %1 S/?E E++%+ !/SPAB E++%+D’.

/f the condition occurs< the code in the %1 S/?E E++%+ phrase is

performed< and the content of the destination field remains unchanged.

/f the %1 S/?E E++%+ phrase is not specified< the assignment is

carried out ith truncation.

There is no %1 S/?E E++%+ support for the 'O0E statement

9i;ed'point overflo. !ivision by 3 can also be trapped.



On O,erflo) Syn Cla$se ; Sla5 Byte

ON O0E2#LOW an be oded 9it7 S,2ING and

UNS,2ING. If t7ere is S,2ING tr$nation t7en t7e

i63erati1e state6ents follo9ed ON O0E2#LOW 9ill be

e<e$ted.

SB1C clause is specified ith C%&P< C%&P'( and C%&P')

items. These items are e;pected to start at half$full$double

ord boundaries for faster address resolution. SB1C clause

does this but it may introduce slac, bytes "unused bytes#

before the binary item.

3( -S'TEST.

(3 -S'0A+( P/C "3)#.

(3 -S'0A+) P/C S2"F# C%&P SB1C.



RETURN-CO'E

+ETU+1'C%!E is a special register and its content is moved to

register(8 hen the control is given bac, to %S. So move the return

code to this register in the program.

+ETU+1'C%!E should not be declared in your program.

E; &%0E (333 to +ETU+1'C%!E. 'A= 4*)>

This sets return code as (333 for the step as 'A=CC that e;ecutes this

program.



ABEN' CO'E

WO2?ING+S,O2AGE SEC,ION.

* WS+A (IC )-".

* WS+B (IC )-".

* WS+C (IC )-".

@@ WS+AB+CO&E (IC S)-4 CO'(.

(2OCE&U2E &I0ISION.

'AIN+(A2A.

ACCE(, WS+A.

ACCE(, WS+B.

CO'(U,E WS+C WS+A WS+B ON SIE E22O2

'O0E ** ,O WS+AB+CO&E. 'A= 8)"

CALL DILBOABN*D USING WS+AB+CO&E.

&IS(LA WS+C.

S,O( 2UN.



Than. /ou

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COBOL_Training_Class-9.ppsx