Q-cons, CXDs, and DXDs enlist the help of the Binder to make it easy for you to allocate storage dynamically for all your CSECTS. They also widen the possibilities for how you can design multi-CSECT programs. Some companies use these ideas to promote the separation of storage and code. In any case, this is an interesting HLASM path to explore.
I’ve created a video to explain these ideas and a sample program listed below that you can use as skeleton code for further exploration.
PRINT ON,NODATA,NOGEN
**********************************************************************
********************** STORAGE FOR ASECT ****************************
**********************************************************************
ASTOR DSECT
A1 DS CL80 SOME VARIABLES FOR ASECT
A2 DS CL30
A3 DS CL5
A4 DS PL10
A5 DS 200CL5
SAVEA DS 18F AREA FOR MY CALLEE TO SAVE & RESTORE MY REGS
**********************************************************************
********************** STORAGE FOR PARMS ****************************
**********************************************************************
PARMSECT DSECT
X DS CL80
Y DS CL80
Z DS CL80
**********************************************************************
********************** ASECT CONTROL SECTION ***********************
**********************************************************************
ASECT CSECT
ASECT AMODE 31
ASECT RMODE 24
********************** ENTRY LOGIC *********************************
STM 14,12,12(R13) SAVE CALLER'S REGS
BASR R12,0 ESTABLISH
USING *,R12 ADDRESSABILITY
L R8,EDSLEN GRAB LENGTH OF STORAGE NEEDED
STORAGE OBTAIN,LENGTH=(R8),ADDR=(R11)
LR R10,R11 GRAB ADDRESS FOR ALL STORAGE
A R10,ASECTO ADD OFFSET FOR MY DSECT
USING ASTOR,R10 I HAVE ADDRESSABILITY
ST R13,SAVEA+4 BACK-CHAIN CALLER'S FROM MINE
LA R13,SAVEA POINT TO MY LOWER-LEVEL SA
********************** BEGIN LOGIC *********************************
OPEN (FILEOUT,(OUTPUT))
PUT FILEOUT,=CL80'ENTERING PROGASECT'
LR R9,R11 POINT AT DYNAMIC STORAGE
A R9,PARMO ADD THE OFFSET FOR PARMS
USING PARMSECT,R9 I HAVE ADDRESSABILITY
MVC X,=CL80'THIS IS PARM X' INITIALIZE ...
MVC Y,=CL80'THIS IS PARM Y' ... PARMS
MVC Z,=CL80'THIS IS PARM Z'
LA R1,=A(FILEOUT,PARMO) PASS THE DCB AND PARMO
L R15,=A(BSECT) CALLING BSECT
BASR R14,R15 BRANCH THERE
PUT FILEOUT,=CL80'RETURNED TO PROGA1'
LR R9,R11 POINT AT ALLOCATED STORAGE
A R9,XXXAO ADD THE OFFSET TO XXX
PUT FILEOUT,0(R9) R9 POINTS AT XXX
CLOSE FILEOUT
STORAGE RELEASE,LENGTH=(R8),ADDR=(R11)
*********************** STARDARD EXIT ********************************
RETURN EQU * BRANCH TO HERE FOR NORMAL RETURN
L R13,SAVEA+4 POINT TO CALLER'S SAVE AREA
LM R14,R12,12(R13) RESTORE CALLER'S REGS
LA R15,0 SET RETURN CODE REG 15 = 0
BR R14
****************** LOCAL DATA AREAS ********************************
FILEOUT DCB DSORG=PS, X
MACRF=(PM), X
DEVD=DA, X
DDNAME=FILEOUT, X
RECFM=FB, X
LRECL=80
ASECTO DC Q(ASTOR) OFFSET TO ASTOR
PARMO DC Q(PARMSECT) OFFSET TO PARMSECT
XXX DXD CL80 DECLARATION OF XXX IN EDS
XXXAO DC Q(XXX) OFFSET TO XXX
EDSLEN CXD FULLWORD TOTAL SPACE NEEDED
LTORG
YREGS
**********************************************************************
********************** STORAGE FOR BSECT ****************************
**********************************************************************
BSTOR DSECT
B1 DS F THE STORAGE AREAS NEEDED IN BSECT
B2 DS CL20
B3 DS PL5
B4 DS CL100
B5 DS CL5
SAVEB DS 18F BSECT SAVE AREA
**********************************************************************
********************** BSECT CONTROL SECTION ***********************
**********************************************************************
BSECT CSECT
STM 14,12,12(R13) SAVE CALLER'S REGS
BASR R12,0 ESTABLISH
USING *,R12 ADDRESSABILITY
LR R10,R11 SET UP...
A R10,BSECTO ... ADDRESSABILITY FOR BSECT
USING BSTOR,R10 I HAVE STORAGE ADDRESSABILITY
LR R9,R11 POINT AT ALLOCATED MEMORY
L R6,4(R0,R1) R6 POINTS AT PARMO
A R9,0(R0,R6) ADD THE OFFSET FOR PARMS
USING PARMSECT,R9 I HAVE PARM ADDRESSABILITY
ST R13,SAVEB+4
LA R13,SAVEB
********************** BEGIN LOGIC *********************************
L R5,0(R0,R1) R5 POINTS AT MY RECOUT DCB
PUT (R5),=CL80'ENTERED BSECT'
PUT (R5),X PRINT THE PARMS
PUT (R5),Y
PUT (R5),Z
*
* USE BSTOR FIELDS CAN BE USED HERE
*
MVC B4,=CL80'THIS IS B4 DATA'
PUT (R5),B4
*
* PREPARE TO USE XXX
*
LR R9,R11 POINT AT XDS WITH R9
A R9,XXXBO ADD THE OFFSET TO XXX
MVC 0(80,R9),=CL80'XXX IN ASECT WAS CHANGED IN BSECT'
*
PUT (R5),=CL80'ABOUT TO LEAVE BSECT'
*********************** STARDARD EXIT ********************************
L R13,SAVEB+4 STANDARD EXIT CODE
LM R14,R12,12(R13)
BR R14
************* INITIALIZED DATA AREAS AND PARMS ***********************
BSECTO DS Q(BSTOR) OFFSET FOR BSECT STORAGE
XXXBO DC Q(XXX) OFFSET TO XXX
LTORG
END ASECT
