MSLINK macro

Logical links are assigned to physical links during system definition (using the MSPLINK keyword) or dynamically with /MSASSIGN or UPDATE MSLINK commands.

You can define a maximum of 1018 logical links (MSLINK macros) in an IMS system.

Dynamic definition

Logical links can be defined dynamically with the CREATE MSLINK command, instead of defining them statically with the system definition MSLINK macro.

Supported environments

The MSLINK macro can be used in the DB/DC and DCCTL environments.

Syntax

Label field

The label field specifies a 1- to 8-character link name that is used by the type-1 UPDATE and type-2 QUERY and UPDATE commands to identify the logical link. If you do not specify a name, a default name is assigned, DFSLxxxx, where xxxx is the logical link number that system generation assigns to the link. That name is used in the QUERY and UPDATE commands. The logical link name can be changed with the UPDATE MSLINK command.

Positional parameters

The MSLINK macro does not include positional parameters.

Keyword parameters

To find which parameters apply to your IMS configuration, refer to Selecting the appropriate macros to define your system.

BACKUP=

For XRF-capable IMS systems, controls the automatic restart of TCP/IP and VTAM® links after an XRF takeover.

When specified on the MSLINK macro, BACKUP overrides switching options specified on the definition of the associated physical link. Use only if HSB=YES is specified on the IMSCTRL macro.

X is a numeric integer from 1 to 7, inclusive. It sets priorities for reestablishing the session. When either the BACKUP keyword is omitted or no value is specified for BACKUP on either the MSPLINK macro or the MSLINK macro, the default is 4. NO suppresses the session recovery of the MSC physical link at takeover.

Although BACKUP prioritizes the order in which IMS restarts TCP/IP and VTAM links, the active requests might be completed in any order because of variables such as internal VTAM conflicts and pacing, TCP/IP network traffic, and so on.

MODETBL=

Specifies the name of the VTAM logon mode table entry (logon mode name) containing the SNA bind parameters to be used when a session is established for this terminal. The maximum is 255 unique names for each IMS system.

This function allows a system definition specification for referencing an entry other than the default entry in the user's VTAM logon mode table.

With this function, if MODETBL= is not specified at system definition, no functional or operational change affects the user.

If MODETBL= is specified at system definition, the specified entry name is used.

You can display the current MODETBL name using either the /DISPLAY command or the QUERY MSLINK command. You can override the MODETBL name by using any of the following commands:

• The VARY ACT, LOGON= command by the network terminal operator
• The /RST or the /CHANGE command by the master terminal operator
• The type-2 command UPDATE MSLINK NAME(linkname) SET(MODETBL(modetablename)) through the OM API

If the VTAM-node=name being defined is in another domain (that is, a cross-domain resource), the MODETBL parameter need not be specified.

Related reading: See z/OS® Communications Server: SNA Programming for additional information.

MSPLINK=

This operand identifies the physical link to which this logical link is assigned. If you do not specify this operand, no assignment to a physical link is made during system definition. You can assign this logical link to a physical link later by using either the /MSASSIGN command or the type-2 command UPDATE MSLINK NAME(linkname) SET(MSPLINK(msplinkname)). You must assign the logical link to a physical link before communication can be established between the two systems.

When specified, the MSPLINK macro must be defined before the MSLINK macro.

OPTIONS=

This parameter allows you to specify certain options for session initiation and restart. The specifications made on this OPTIONS parameter must be consistent with the MSLINK OPTIONS specification in the partner systems.

The OPTIONS parameter is valid for MSC TCP/IP and MSC VTAM links only.

You can specify the following values on the OPTIONS= keyword:

SYNCSESS|FORCSESS

SYNCSESS indicates that session initiation is to be completed only if session resynchronization is successful. Successful session resynchronization occurs when the message sequence numbers of the two logical units in session agree, or when the sequence number of the sender is not less than the sequence number of the receiver. The default is SYNCSESS.

FORCSESS forces the session to be completed regardless of whether session resynchronization is successful.

During IMS execution, this option can be overridden by either the type-1 command /CHANGE LINK nn FORCSESS|SYNCSESS|COLDSESS or the type-2 command UPDATE MSLINK NAME(linkname) SET(SYNCOPT(FORCSESS|SYNCSESS|COLDSESS)).

ASR|NOASR

When using the Session Outage Notification facility, specifies whether automatic session restart (ASR) processing is enabled for a defined node. NOASR is the default.

The ASR|NOASR option does not apply to MSC TCP/IP links.

ASR works only if both sides of the link are using the ASR option.

Specifying ASR or NOASR on the MSLINK macro overrides ASR specifications on the TYPE and MSPLINK macros.

To display the current ASR option you can use either of the following commands:

• The type-1 command /DISPLAY
• The type-2 command QUERY MSLINK NAME(linkname) SHOW(STATUS)

To change the current ASR option you can use either

• The type-1 command /CHANGE
• The type-2 command UPDATE MSLINK NAME(linkname) SET(ASR(OFF|ON))

PARTNER=

The value for partner-id is a two-character alphanumeric identification. It ensures that the two related logical links in two systems are always logically and physically connected. Both systems must have MSLINK macro statements with the same value for partner-id. A logical link can be assigned to a different physical link; the two systems still communicate through the logical link, which remains as defined.

You can modify the partner ID by using the type-2 command UPDATE MSLINK NAME(linkname) SET(PARTNER(partner-id)).