If your CICS® installation is to use CICS-to-IMS™ intersystem communication, you must ensure that the CICS and the IMS
installations are fully compatible.
The following sections are intended to help you communicate effectively
with the person responsible for installing the IMS system. They may
also be helpful if you have that responsibility. You should also
refer to Defining links to remote systems, especially the section on defining
compatible CICS and IMS nodes. For full details of IMS installation,
refer to the IMS/ESA Installation Guide.
When the IMS system is defined to VTAM®, the
following operands should be included on the VTAM
APPL statement:
- AUTH=(ACQ,VPACE)
- ACQ is required to allow IMS to acquire LU type 6 sessions.
VPACE is required to allow pacing of the intersystem flows.
- VPACING=number
- This operand specifies the maximum number of normal-flow requests
that another logical unit can send on an intersystem session before
waiting to receive a pacing response. An initial value of 5 is suggested.
- EAS=number
- The number of network addressable units must include the total
number of parallel sessions for this IMS system.
- PARSESS=YES
- This operand specifies LU type 6 parallel session support.
For further information about the VTAM APPL statement, see the OS/390 eNetwork Communications Server: SNA Resource Definition Reference manual.
ACF/VTAM LOGMODE table entries for IMS
IMS allows the user to specify some BIND parameters in a VTAM logmode table entry. The CICS
logmode table entry must match that of the IMS system. IMS uses (in
order of priority) the mode table entry specified in:
- The MODETBL parameter of the TERMINAL macro
- The mode table entry specified in CINIT
- The DLOGMODE parameter in the VTAMLST APPL statement or the MODE
parameter in the IMS /OPNDST command
- The ACF/VTAM defaults.
Figure 31 shows a typical IMS logmode table entry:
Figure 31. A typical IMS logmode table entry
LU6NEGPS MODEENT LOGMODE=LU6NEGPS, NEGOTIABLE BIND
PSNDPAC=X'01', PRIMARY SEND PACING COUNT
SRCVPAC=X'01', SECONDARY RECEIVE PACING COUNT
SSNDPAC=X'01', SECONDARY SEND PACING COUNT
TYPE=0, NEGOTIABLE
FMPROF=X'12', FM PROFILE 18
TSPROF=X'04', TS PROFILE 4
PRIPROT=X'B1', PRIMARY PROTOCOLS
SECPROT=X'B1', SECONDARY PROTOCOLS
COMPROT=X'70A0', COMMON PROTOCOLS
RUSIZES=X'8585', RU SIZES 256
PSERVIC=X'060038000000380000000000' SYSMSG/Q MODEL
MODEEND
This section summarizes the IMS ISC-related macros and parameters that
are used in IMS system definition. You should also refer to Defining compatible CICS and IMS nodes. For full details of IMS installation, refer to
the installation guide for the IMS product.
The COMM macro
- APPLID=name
- Specifies the applid of the IMS system. For an IMS system generated
without XRF support, this is usually the name that you should specify
on the NETNAME option of DEFINE CONNECTION when you define the IMS
system to CICS.
However, bear the following in mind:
- For an IMS system with XRF, the CICS NETNAME option should specify
the USERVAR (that is, the generic applid) that is defined in the DFSHSBxx
member of IMS.PROCLIB, not the applid from the COMM macro.
- If APPLID on the COMM macro is coded as NONE, and XRF is not used,
the CICS NETNAME option should specify the label on the EXEC statement
of the IMS startup job.
- If the IMS system is started as a started task, NETNAME should
specify the started task name.
For an explanation of how IMS system names are specified,
see topic System names.
- RECANY=(number,size)
- Specifies the number and size of the IMS buffers that are used
for VTAM "receive any" commands. For ISC sessions, the buffer
size has a 22-byte overhead. It must therefore be at least 22 bytes
larger than the CICS buffer size specified in the SENDSIZE option
of DEFINE SESSIONS.
This size applies to all other ACF/VTAM terminals
attached to the IMS system, and must be large enough for input from
any terminal in the IMS network.
- EDTNAME=name
- Specifies an alias for ISCEDT in the IMS system. For CICS-to-IMS
ISC, an alias name must not be longer than four characters.
The TYPE macro
- UNITYPE=LUTYPE6
- Must be specified for ISC.
Parameters of the TERMINAL macro can also be specified in the TYPE
macro if they are common to all the terminals defined for this type.
The TERMINAL macro
The TERMINAL macro identifies the remote CICS system to IMS. It
therefore serves the equivalent purpose to DEFINE CONNECTION in CICS.
- NAME=name
- Identifies the CICS node to IMS. It must be the same as the
applid of the CICS system (the generic applid for XRF systems).
- OUTBUF=number
- Specifies the size of the IMS output buffer. It must be equal
to or greater than 256, and should include the size of any function
management headers sent with the data. It must not be greater than
the value specified in the RECEIVESIZE option of the DEFINE SESSIONS
commands for the intersystem sessions.
- SEGSIZE=number
- Specifies the size of the work area that IMS uses for deblocking
incoming messages. We recommend that you use the size of the longest
chain that CICS may send. However, if IMS record mode (VLVB) is used
exclusively, you could specify the largest record (RU) size.
- MODETBL=name
- Specifies the name of the VTAM mode table entry to be used.
You must omit this parameter if the CICS system resides in a different
SNA domain.
- OPTIONS=[NOLTWA|LTWA]
- Specifies whether Log Tape Write Ahead (LTWA) is required.
For LTWA, IMS logs session restart information for all active parallel
sessions before sending a syncpoint request. LTWA is recommended
for integrity reasons, but it can adversely affect performance. NOLTWA
is the default.
- OPTIONS=[SYNCSESS|FORCSESS]
- Specifies the message resynchronization requirement following
an abnormal session termination. SYNCSESS is the default. It requires
both the incoming and the outgoing sequence numbers to match (or CICS
to be cold-started) to allow the session to be restarted. FORCSESS
allows the session to be restarted even if a mismatch occurs. SYNCSESS
is recommended.
- OPTIONS=[TRANSRESP|NORESP|FORCRESP]
- Specifies the required response mode.
- TRANSRESP
- Specifies that the response mode is determined on a transaction-by-transaction
basis. This is the default.
- NORESP
- Specifies that response-mode transactions are not allowed.
In CICS terms, this means that a CICS application cannot initiate
an IMS transaction by using a SEND command, but only with a START
command.
- FORCRESP
- Forces response mode for all transactions. In CICS terms, this
means that a CICS application cannot initiate an IMS transaction by
using a START command, but only by means of a SEND command.
TRANSRESP is recommended.
- OPTIONS=[OPNDST|NOPNDST]
- Specifies whether sessions can be established from this IMS
system. OPNDST is recommended.
- {COMPT1|COMPT2|COMPT3|COMPT4}={SINGLEn|MULTn}
- Specifies the IMS components for the IMS ISC node. Up to four
components can be defined for each node. The input and output components
to be used for each session are then selected by the ICOMPT and COMPT
parameters of the SUBPOOL macro.
The following types of component
can be defined:
- SINGLE1
- Used by IMS for asynchronous output. One output message is
sent for each SNA bracket. The message may or may not begin the bracket,
but it always ends the bracket.
- SINGLE2
- Each message is sent with the SNA change-direction indicator
(CD).
- MULT1
- All asynchronous messages for a given LTERM are sent before
the bracket is ended. The end bracket (EB) occurs after the last
message for the LTERM is acknowledged and dequeued.
- MULT2
- The same as MULT1, but CD is sent instead of EB.
- SESSION=number
- Specifies the number of parallel sessions for the link. Each
session is represented by an IMS SUBPOOL macro and by a CICS DEFINE
SESSIONS command.
- EDIT=[{NO|YES}][,{NO|YES}]
- Specifies whether user-supplied physical output and input edit
routines are to be used.
The VTAMPOOL macro
The SUBPOOL macro heads the list of SUBPOOL macros that define
the individual sessions to the remote system.
The SUBPOOL macro
A SUBPOOL macro is required for each session to the remote system.
- NAME=subpool-name
- Specifies the IMS name for this session. A CICS-to-IMS session
is identified by a "session-qualifier pair" formed from the
CICS name for the session and the IMS subpool name.
The CICS name
for the session is specified in the SESSNAME option of the DEFINE
SESSIONS command for the session.
The IMS subpool name is specified
to CICS in the NETNAMEQ option of the DEFINE SESSIONS command.
The NAME macro
The NAME macro defines the logical terminal names associated with
the subpool. Multiple LTERMs can be defined per subpool.
- COMPT={1|2|3|4}
- Specifies the output component associated with this session.
The component specified determines the protocol that IMS ISC uses
to process messages. An output component defined as SINGLE1 is strongly
recommended.
- ICOMPT={1|2|3|4}
- Specifies the input component associated with this session.
When IMS receives a message, it determines the input source terminal
by finding the NAME macro that has the matching input component number.
A COMPT1 input component must be defined for each session that CICS
uses to send START commands.
- EDIT=[{NO|YES}][,{ULC|UC}]
- The first parameter specifies whether the user-supplied logical
terminal edit routine (DFSCNTEO) is to be used.
The second parameter
specifies whether the output is to be translated to uppercase (UC)
or not (ULC) before transmission.
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