Thanks done
The org *-2 wipes the SVC
MVC SNAPL_AUTO(SNAPL_LEN),SNAPL_STATIC
L R7,START1
SETRP RC=4,RETREGS=YES,RETADDR=(R4),FRESDWA=YES,DUMP=YES,
RECORD=YES,RUB=(R3),DUMPOPX=SNAPL_AUTO
SNAPL_AUTO SNAPX MF=L
SNAPL_AUTO DS 0F
DC AL1(0)
DC AL1(112)
DC AL1(133)
DC AL1(1)
DC AL1(0)
DC AL1(0)
DC AL1(0)
DC AL1(0)
DC A(0)
DC A(0)
DC A(0)
DC A(0)
SNAPX DCB=*-*,PDATA=ALL,SDATA=LSQA,LIST=(R7),STRHDR=L1,
MF=(E,SNAPL_AUTO)
LA 1,SNAPL_AUTO
MVI 3(1),1 SET VERSION NUMBER
LA 0,*-* GET DCB ADDRESS @L1C
ST 0,8(0,1) STORE INTO PARAMETER LIST Y
OI 1(1),115 SET OPTION FLAGS Y
OI 2(1),133 SET OPTION FLAG 2 @G8
MVI 4(1),32 SET OPTION FLAGS Y
MVI 5(1),0 SET OPTIONS FLAGS G3
MVI 6(1),191 SET OPTION FLAGS Y
SDWARC1,R8 DBGREST,R12,R3 WS_DSECT,R13
Statement HLASM R6.0 20
ST (R7),16(0,1) SNAPSHOT LIST ADDR INTO PARAM LIST Y
LA 0,L1 GET HEADER ADDRESS G3
ST 0,20(0,1) STORE HEADER ADDRESS G3
SVC 51
ORG *-2
-----Original Message-----
From: IBM Mainframe Assembler List <[email protected]> On
Behalf Of Peter Relson
Sent: Thursday, November 8, 2018 12:16 PM
To: [email protected]
Subject: Re: Snap Macro Assembler error ? Here it is thanks
<snip>
SETRP RC=4,RETREGS=YES,RETADDR=(R4),FRESDWA=YES,DUMP=YES, X
RECORD=YES,RUB=(R3),DUMPOPX=SNAPL
SNAPL SNAPX DCB=*-*,PDATA=ALL,SDATA=LSQA,LIST=(R7),STRHDR=L1
</snip>
That is not going to work for at least two reasons. One is that, as Walt
pointed out, the "LIST" operand isn't going to get set.
The second is that "SNAPL" is not the address of the parameter list in this
expansion. It is the address of the first instruction of the expansion which
is a branch around the expansion. And relying on there being exactly 4 bytes
from SNAPL to the beginning of the parameter area staying that way forever
would be foolhardy.
If you want to play for now, with no reliance on this working at any time in
the future, you could consider invoking SNAPX but then having ORG *-2 after
the invocation (and continuing your program from there). The last
instruction of the expansion happens to be "SVC 51" so you would end up
no-oping the actual invocation of the service. This too is something that
would be foolhardy to rely upon.
But if you wanted to try, it would be something like this, assuming a
reentrant module:
<in your module storage>
SNAPL_STATIC SNAPX MF=L
<in your dynamic storage>
SNAPL_AUTO SNAPX MF=L
SNAPL_LEN EQU *-SNAPL_AUTO
<in your module storage>
MVC SNAPL_AUTO(SNAPL_LEN),SNAPL_STATIC
SNAPX <all_your_options>,MF=(E,SNAPL_AUTO)
ORG *-2
SETRP <all_your_options>,DUMPOPX=SNAPL_AUTO
Or, use the list form of SNAPX, examine the expansion of an execute form of
SNAPX that does any piece that the list form that you can't do (such as the
processing of LIST=(R7) ), and code that yourself to update your list form
(and/or use the IHASNAPX macro from 'sys1.modgen' to help do that if you
want your code to be more readable). This approach, if you get it right,
will likely work forever, unclean as it might be, because you are producing
exactly the same parameter area that would have been passed to the SNAP
service. But only if you get every bit and byte correct.
You won't need to specify DCB for this SNAPX. That information is not used
for SETRP DUMPOPX.
Peter Relson
z/OS Core Technology Design
