Example MVS Console Interface

The program below is written in MVS Assembler.
It tests a call to the FTP2 program, which is possible because all of its parameters were in the SYSIN DDNAME in the JCL.
If a bad return code is received from FTP2, then the server was down. Console Operators will be given a choice of Continuing anyway, Abending, or Waiting (and retrying).
Continuing will zero out the return code to allow subsequent scheduled jobs in the batch system to continue processing.The Wait & Retry is a good way to avoid having to page the Oncall Programmer, while also not needing to continually restart a job.

TESTFTP CSECT
TESTFTP AMODE 24
TESTFTP RMODE 24
*
R0 EQU 0
R1 EQU 1
R2 EQU 2
R3 EQU 3
R4 EQU 4
R5 EQU 5
R6 EQU 6
R7 EQU 7
R8 EQU 8
R9 EQU 9
R10 EQU 10
R11 EQU 11
R12 EQU 12 BASE REGISTER
R13 EQU 13
R14 EQU 14
R15 EQU 15
LENG72 EQU 72
*---------------------------------------------------------------------*
* DAVID YOUNG - THIS WILL TEST THE FTP2 INTERFACE
*---------------------------------------------------------------------*
BEGIN STM R14,R12,12(R13) STORE R14 THRU R12 INTO R13
BALR R12,R0
USING *,R12 USE 12 AS THE BASE REGISTER
ST R13,SAVEAREA+4 STORE R13 CONTENTS AT SAVEAREA+4
LA R13,SAVEAREA LOAD SAVEAREA ADDRESS INTO REG 13
ST R1,PASSR1 KEEP POINTER TO SYSIN
*
MAIN L R1,PASSR1 PASS SYSIN THROUGH THIS PROGRAM
LINK EP=FTP2 DYNAMICALLY
LTR R15,R15 TEST RETURN CODE
BZ EXITPRT IF R15 IS 0, GOTO EXIT
*
ERROR_PROC DS 0H
SR R6,R6 CLEAR COUNTER REGISTER
LA R5,MSG1 POINT TO ARRAY OF MESSAGES
ERROR_LOOP DS 0H
MVC WTOMSG+8(70),0(R5) MOVE A MESSAGE TO WTO AREA
BAS R10,WTOMSG PERFORM WTOMSG ROUTINE
LA R5,70(R5) INCREMENT TO NEXT ARRAY ENTRY
A R6,=F'1' ADD 1 TO # MSGS PROCESSED
C R6,=F'7' HAVE WE REACHED 7 MSGS?
BL ERROR_LOOP NO, CONTINUE LOOP
ISSUE_WTOR DS 0H
*/ ISSUE WTOR TO GET OPERATOR'S FEEDBACK /*
XC ECBADDR,ECBADDR
WTOR TEXT=(QSTMSG,REPLYAREA,LENG72,ECBADDR), X
CONSNAME=DESTCON, X
RPLYISUR=IDSAREA
WAIT ECB=ECBADDR
*
SR R4,R4 CLEAR COUNTER REGISTER
LA R5,REPLYAREA POINT TO REPLY AREA
SCAN_LOOP DS 0H
CLC ABEND_CONST(5),0(R5) 'ABEND' FOUND?
BE ABEND_EXIT THEN GOTO ABEND_EXIT
CLC CONT_CONST(4),0(R5) 'CONT' FOUND?
BE CONT_EXIT THEN GOTO CONT_EXIT
CLC WAIT_CONST(4),0(R5) 'WAIT' FOUND?
BE WAIT_EXIT THEN GOTO WAIT_EXIT
LA R5,1(R5) MOVE TO NEXT CHARACTER
A R4,=F'1' ADD 1 TO COUNTER
C R4,=F'60' IS COUNTER = 60?
BL SCAN_LOOP IF NOT, CONTINUE LOOP
B CONT_EXIT IF NO VALID CMD FOUND
* THEN GOTO CONT_EXIT
WTOMSG WTO ' +
',ROUTCDE=11,DESC=7
BR R10
*
CONT_EXIT DS 0H
SR R15,R15
EXITPRT DS 0H CLEAR R15
L R13,SAVEAREA+4 PUT PREV SAVEAREA IN REGISTER 13
L R14,12(R13) LOAD REG 14 WITH DISP 12 ADDR R13
LM R0,R12,20(R13) RESTORE R0 TO R12 FROM DISP 20 ON
SR R15,R15 CLEAR RETURN CODE
BSM 0,R14 BRANCH TO RETURN ADDR , IN R14
*
ABEND_EXIT DS 0H
* WTO 'ABEND EXIT',ROUTCDE=11,DESC=7
L R1,=X'000003E7' ABEND CODE IS U999
SVC 13 ISSUE USER ABEND SVC
L R13,SAVEAREA+4 PUT PREV SAVEAREA IN REGISTER 13
L R14,12(R13) LOAD REG 14 WITH DISP 12 ADDR R13
LM R0,R12,20(R13) RESTORE R0 TO R12 FROM DISP 20 ON
BSM 0,R14
*
WAIT_EXIT DS 0H
* WTO 'WAIT EXIT',ROUTCDE=11,DESC=7
STIMER WAIT,DINTVL=WAIT_INTV WAIT,
B MAIN THEN TRY AGAIN
* (GOTO MAIN LOOP)
DS 0F
SAVEAREA DS 18F REGISTER SAVE AREA
PASSR1 DS F REG 1 SAVE AREA (SYSIN)
ECBADDR DS F ECB FOR WTOR
WAIT_INTV DC X'F0F0F0F0F1F0F0C0' TIME INTERVAL FOR STIMER WAIT
ABEND_CONST DC CL5'ABEND' CONSTANT FOR 'ABEND'
CONT_CONST DC CL4'CONT' 'CONT'INUE
WAIT_CONST DC CL4'WAIT' 'WAIT'
*
DESTCON DC CL8'ALTCON ' ALTERNATE CONSOLE IS DESTINATION
REPLYAREA DC CL72' ' CONSOLE REPLY AREA
QSTMSG DC XL2'0050' LENGTH OF MSG FOR CONSOLE
QMSG DC C'TESTFTP - REPLY '
DC XL1'7D' X'7D' = SINGLE QUOTE
DC C'ABEND'
DC XL1'7D'
DC C', '
DC XL1'7D'
DC C'CONT'
DC XL1'7D'
DC C' OR '
DC XL1'7D'
DC C'WAIT'
DC XL1'7D'
DC CL40' '
IDSAREA DS CL12 CONSOLE ID INFO RETURNED HERE
*MESSAGE AREA*
MSG1 DC CL70'---FTP2 - ERROR OCCURRED. RECEIVING SERVER NOT ACTIVE '
MSG2 DC CL70'---FTP2 - PLEASE NOTIFY IT ONCALL TO ACTIVATE SERVER '
MSG3 DC CL70'---FTP2 - AND SELECT ONE OF THE FOLLOWING OPTIONS: '
MSG4 DC CL70'---FTP2 - WAIT => +RECOMMENDED+ WAIT AND RETRY '
MSG5 DC CL70'---FTP2 - CONT => CONTINUE JOB PROCESSING '
MSG6 DC CL70'---FTP2 - ABEND => JOB WILL ABEND +LAST RESORT+ '
MSG7 DC CL70'---FTP2 ----------------------------------------------'
END

A more readable version of the code is here:  TESTFTP Source