IBM AS/400 manual Pssr, Which is designed to ge, Exceptions Order Show how to avoid looping Within

	*-----------------------------------------------------------------			*
	* Start of subprocedure definition
	*-----------------------------------------------------------------			*
P SubProc		B
D SubProc		PI	5P 0
	...
	*-----------------------------------------------------------------			*
	* Body of code goes here including division operation.
	*-----------------------------------------------------------------			*
C	X	DIV	Divisor	Result
C		Return	Result
	*-----------------------------------------------------------------			*
	* An error occurs when division by zero takes place.
	* Control is passed to the *PSSR subroutine.
	*-----------------------------------------------------------------			*
C	*PSSR	BEGSR
	*-----------------------------------------------------------------			*
	* If this is a divide-by-zero error, return 0 from the subproc￿edure
	*-----------------------------------------------------------------			*
C		IF	Err = 102
C		RETURN	0
C		ENDIF
	*-----------------------------------------------------------------			*
	* If control reaches ENDSR, the procedure will fail
	*-----------------------------------------------------------------			*
C		ENDSR
P		E

Figure 114. Example of Subprocedure *PSSR Subroutine with RETURN

Avoiding

a

Loop

in

an

Error

Subroutine

In the previous example, it is unlikely that

an

error

would

occur

in

thereby

cause

a

loop.

However,

depending

on

how the *PSSR is written

occur

if

an

exception

occurs

while

processing the

*PSSR.

One

way

to

avoid

such

a

loop

is

to

set

a

first-time

switch

in

the

not

the first

time

through the subroutine,

you

can

specify

an

appro

point, such as *CANCL, for

the

Factor

2

entry

of

the ENDSR

operation.

Figure 115

on

page 236

shows

a

program

NOLOOP

which is designed to ge

exceptions in

order

to

show how to avoid looping

within

a

*PSSR

subrou

program

generates an

exception

twice:

1. In the main body of the code, to pass control to the *PSSR

2. Inside the *PSSR to potentially cause a loop.

Chapter 12. Handling Exceptions235