VTAM LINK statements describe the partners with which this node will communicate. If the ACCEPTUI parameter does not specify "Y" (Yes) on the VTAM DRIVER statement, a LINK statement is required for each partner.
The VTAM LINK statement has the following format:
For more information about syntax conventions and rules used in this section, read Conventions.
The LINK statement parameters are read from a sequential file during system startup, and can be modified after startup using the ALTER operator command. Some parameters can be modified when the link is open or closed. Others can be modified only when the link is closed. See ALTER and CLOSE in the section VTAM Operator Commands. The open/closed requirement for each parameter is included in its description.
In the following syntax-example diagrams, the underlined portion of the parameter name is the minimum abbreviation of the parameter.
linkname
This required parameter specifies the name by which this link is to be known; it is positional, and must be specified immediately after the LINK keyword and immediately before the driver name (VTAM); linkname must be unique on the node. All operator commands affecting the link must specify this name.
ACQUIRE={Y | N | YES | NO | ON | OFF}
This parameter is optional. ACQUIRE=Y (or "YES" or "ON") instructs Entire Net-Work to attempt to establish communications with this partner node as part of initialization. ACQUIRE=N (or "NO" or "OFF") instructs Entire Net-Work to wait for the partner to establish communications, or to wait for operator intervention. The default is N. The ACQUIRE parameter can be modified only when the link is closed.
This parameter is ignored for VAX and UNIX partners, which do not currently support session initiation from the IBM mainframe.
APPLID=partner's-vtam-name
This optional parameter specifies this partner's VTAM application name. Specify the 1 - 8 character value from the ACBNAME parameter of the APPL macro that was used to define this partner to VTAM. If the ACBNAME parameter is omitted from the APPL macro, specify the 1 - 8 character label on the APPL macro. This parameter is synonymous with the LUNAME parameter. If both parameters are specified, the second one is used. If neither parameter is specified, or if the specified value contains wildcard characters, this link is considered a "model" link. (See the section Model Links.)
ASSOCLU=partner's receive lu
This optional parameter specifies the VTAM name of the LU6.2 partner's Receive LU. The partner's Entire Net-Work simulates full duplex communication with the LU6.2 protocol by establishing two sessions with the VTAM line driver. The first session uses the LU specified by the LUNAME parameter in this LINK statement. The second session uses the LU specified by the ASSOCLU parameter. If you are using parallel sessions, omit the ASSOCLU parameter, or specify the same LU name for both parameters. Value may be from 1 - 8 characters in length. The ASSOCLU parameter can be modified only when the link is closed.
BLOCKMSG={Y | N | YES | NO | ON | OFF}
Specify BLOCKMSG=Y to instruct Entire Net-Work to block as many messages as possible into one buffer for transmission to this partner. This parameter is reset to N for all partner types except IBM. The default is N. The BLOCKMSG parameter can be modified when the link is open or closed.
COMPRMSG={Y | N | YES | NO | ON | OFF}
Specify COMPRMSG=Y to instruct Entire Net-Work to attempt to compress duplicate characters out of the message before transmission to this partner. This parameter is reset to N for all partner types except IBM. The default is N. The COMPRMSG parameter can be modified when the link is open or closed.
CRYPT={Y | N | YES | NO | ON | OFF}
Specify CRYPT=Y to instruct Entire Net-Work to request that VTAM encrypt data before sending it to this partner and decrypt data received from this partner. This parameter is reset to N for all partner types except IBM. The default is N. The CRYPT parameter can be modified only when the link is closed.
DEFRESP={Y | N | YES | NO | ON | OFF}
Specify DEFRESP=Y to instruct Entire Net-Work to request that this partner acknowledge receipt of each buffer by returning a definite response. The default is N. The DEFRESP parameter can be modified when the link is open or closed.
Note:
Setting DEFRESP=Y may result in performance degradation.
EXIT=name
This parameter specifies the name of a user exit. For more information, see the section User Exit Interface.
If a user exit is specified and the SAF parameter is set to Y or L, incoming requests are made available to the user exit before NETSAF is called.
If EXIT is coded but the load module cannot be loaded, execution continues as if no exit were specified. The EXIT parameter can be modified only when the link is closed.
LOGMODE=partner's-logmode-table-name
This optional parameter specifies the name of the logmode table to be used for outbound connections to this partner and can be from 1 - 8 characters in length. This logmode table module is loaded at link initialization; therefore, the module must reside in one of the STEPLIB data sets. The LOGMODE parameter can be modified only when the link is closed.
LUNAME=partner's-vtam-name
This optional parameter specifies this partner's VTAM LU name. Specify the 1 - 8 character label from the LU statement used to define this partner to VTAM. This parameter is synonymous with the APPLID parameter. If both parameters are specified, the second is used. If neither parameter is specified, or if the specified value contains wildcard characters, this link is considered a "model" link. (See the section Model Links.)
MAXBLK={ru-size | 1024}
This parameter specifies the maximum size, in bytes, of the buffer used to send data to this partner. The maximum size can also be specified with the MAXRU parameter. If values are specified for both parameters, the larger value is used. The MAXBLK parameter can be modified only when the link is closed.
Specify a decimal value from the MAXRU table shown below. Optionally, a value followed by a multiplier of either "M" (x 1048576, or 1 MB) or "K" (x 1024, or 1 KB) can be specified. The value can be 128 - 491520. A value less than 128 is reset to 128. A value greater than 128 but not matching one of those in the MAXRU table is reduced to the nearest table value. The default value is 1024.
MAXRU= {maximum buffer size | 87}
This parameter specifies the maximum size, in bytes, of the buffer used to send data to this partner. The maximum buffer size can also be specified with the MAXBLK parameter. If values are specified for both parameters, the larger value is used.
The MAXRU specification is determined by the following equation:
bytes = 1st hex digit * (2 raised to the 2nd hex digit power)
For example:
87 = 8 * (2 to the 7th power) = 8 * 128 = 1024
Specify a hexadecimal value from the MAXRU table shown below. The value can be 84 - FF. A value less than 84 is reset to 84. A value greater than 84 but not matching one of those in the MAXRU table is reduced to the nearest table value. The default value is 87.
| Hex Value of Bits 4-7 |
8 |
9 |
A |
B |
C |
D |
E |
F |
| 4 | 128 | 144 | 160 | 176 | 192 | 208 | 224 | 240 |
| 5 | 256 | 288 | 320 | 352 | 384 | 416 | 448 | 480 |
| 6 | 512 | 576 | 640 | 704 | 768 | 832 | 896 | 960 |
| 7 | 1024 | 1152 | 1280 | 1408 | 1536 | 1664 | 1792 | 1920 |
| 8 | 2048 | 2304 | 2560 | 2816 | 3072 | 3328 | 3584 | 3840 |
| 9 | 4096 | 4608 | 5120 | 5632 | 6144 | 6656 | 7168 | 7680 |
| A | 8192 | 9216 | 10240 | 11264 | 12288 | 13312 | 14336 | 15360 |
| B | 16384 | 18432 | 20480 | 22528 | 24576 | 26624 | 28672 | 30720 |
| C | 32768 | 36864 | 40960 | 45056 | 49152 | 53248 | 57344 | 61440 |
| D | 65536 | 73728 | 81920 | 90112 | 98304 | 106496 | 114688 | 122880 |
| E | 131072 | 147456 | 163840 | 180224 | 196608 | 212992 | 229376 | 245760 |
| F | 262144 | 294912 | 327680 | 360448 | 393216 | 425984 | 458752 | 491520 |
MINCMP=minimum-length-for-compression
This optional parameter specifies the minimum number of consecutive, identical bytes required for compression. Value can be 5 - 65535. A value less than 5 is reset to 5. This parameter is ignored if COMPRMSG=NO. The MINCMP parameter can be modified when the link is open or closed.
MODEENT= {SAGVTAM | logmode-table-entry-name}
This optional parameter specifies the name of the entry in the logmode table to be used for outbound sessions with this partner. The entry name can be 1-8 characters and must exist in the logmode table specified by the LOGMODE parameter for this LINK statement. The default value is SAGVTAM. The MODEENT parameter can be modified only when the link is closed.
NETID=partner's-VTAM-network-ID
This optional parameter specifies the partner's VTAM network ID. The values assigned to the NETID parameter and the APPLID parameter are combined to form the partner's fully qualified network name. The NETID parameter can be modified only when the link is closed.
PSTATS={N | Y}
This optional parameter determines whether or not (Y or N) statistics are printed to DDPRINT when the statistics interval expires. The default value is PSTATS=Y. This parameter does not affect the STATS operator command. The PSTATS= parameter can be modified when the link is open or closed.
RESTART= (i,n)
This optional parameter specifies the retry interval in seconds (i) and the number of retries (n) that will be made to start the connection to the remote node. If RESTART is not specified, or (i) is specified as zero, no retry is attempted. By specifying (n) as zero, an infinite number of retries can be requested.
The TIMER parameter on the NODE statement affects the RESTART parameter (see the section Entire Net-Work NODE Statement. The retry interval should not be less than the TIMER parameter, and should be a multiple of this value. If a retry interval other than zero is specified that is less than the value of the TIMER parameter, the TIMER value is used instead. The RESTART parameter can be modified when the link is open or closed.
RSTATS={N | Y}
This optional parameter determines whether or not (Y or N) statistics are automatically reset to zero when the statistics interval expires. The default value is RSTATS=N. The RSTATS parameter can be modified when the link is open or closed.
SAF={Y | L | N}
If SAF=Y or SAF=L is specified, Entire Net-Work will call the SAF Interface for all incoming requests on this link; failure to load the Interface is considered a security violation and Entire Net-Work will shut down. If SAF=L, the calls are traced and the output directed to DDPRINT. An error code is transmitted to the user if access to SAF is denied. If a user exit is specified by the EXIT parameter and the SAF parameter is set to Y or L, incoming requests are made available to the user exit before NETSAF is called. The SAF parameter can be modified when the link is open or closed. The default value is N (No).
SNDTMOUT={send-timeout | 10}
This optional parameter defines the amount of time, in seconds, that the VTAM line driver will wait for a message to be received by the partner's VTAM link. When the SNDTMOUT value is exceeded, the link is disconnected and message NETV039I is issued. The default value is 10. The SNDTMOUT parameter can be modified when the link is open or closed.
STATBLK={Y | N | YES | NO | ON | OFF}
This optional parameter specifies whether or not statistics about the blocking of messages are to be collected. This parameter is ignored if BLOCKMSG=N. The STATBLK parameter can be modified when the link is open or closed.
STATCMP={Y | N | YES | NO | ON | OFF}
This optional parameter specifies whether or not statistics about data compression are to be collected. This parameter is ignored if COMPRMSG=N. The STATCMP parameter can be modified when the link is open or closed.
STATINT={statistics-interval | 3600}
This optional parameter specifies the amount of time, in seconds, before statistics are automatically reported or reset. Value may be 0 - 2 gigabytes. The default value is 3600. The STATINT parameter can be modified when the link is open or closed.
TRACESIZ= trace-table-size
This optional parameter specifies the size of the VTAM link specific trace table. The TRACESIZ parameter can be modified when the link is open or closed.
The minimum value is 16384 (x'4000') bytes. A value less than 16384 is reset to 16384. The default value is the value of the TRACESIZ DRIVER parameter or, if none is specified, 16384.
The maximum value is 4194304 (x'400000') bytes. A value greater than 4194304 is reset to 4194304.
WEIGHT={relative-weight | 256}
This optional parameter specifies the weight of this link with respect to other links connected to the same node. If a given target can be reached by more than one path (chain of connected links), the path with the lowest weight is used. Slow or expensive links should be given a higher value than fast or inexpensive links. Values range from 1 to 999999. The default is 256. The WEIGHT parameter can be modified when the link is open or closed.
ZEDC={ Y | N }
This parameter indicates whether zEnterprise Data Compression (zEDC) compression can occur for the link. Valid values are "Y" or "N"; "N" is the default. Determination of whether or not zEDC data compression occurs is based on a combination of the settings of this parameter and the ZEDCINIT parameter on the NODE statement, as described in the following table:
| LINK ZEDC Parameter Setting | NODE ZEDCINIT Parameter Setting | Result |
|---|---|---|
| Y | Y | Outbound buffers for the link are compressed. |
| Y | N | Outbound buffers are not compressed. |
| N | Y | Outbound buffers for TCPI links are not compressed, but other outbound buffers might be (depending on the setting of their LINK statement ZEDC parameters). |
| N | N | Outbound buffers are not compressed. |
Note:
If the node-to-node handshake indicates that the destination node
does not support zEDC data compression, the outbound payload will not be
compressed, regardless of any zEDC parameter settings on the NODE statement or
any LINK statement.
zEnterprise Data Compression (zEDC) can occur only on z/OS operating systems. Consequently, ZEDC=Y can be specified only on z/OS systems that support zEDC. For complete information on z/OS requirements for zEDC support, refer to IBM documentation regarding zEnterprise Data Compression (zEDC).
When compression occurs it occurs on buffers with sizes greater than the value defined by the NODE statement's ZEDCSZ parameter.
ZEDCLOG={ F | L | N }
This optional parameter indicates what level of trace data will be logged for zEDC compression processing. This trace data logging occurs independently of Entire Net-Work's global tracing parameter setting (LOG=YES or LOG=FULL parameter settings on the NODE statement). Valid values are described in the following table:
| ZEDCLOG Setting | Result |
|---|---|
| F | Trace data is logged prior to and after compression and decompression processing. The amount of data logged is equivalent to the length of the data. |
| L | Trace data is logged prior to and after compression and decompression processing. The amount of data logged is 100 (x'64') bytes. |
| N | This is the default. No trace data is logged. |
Note:
The F and L settings of ZEDCLOG should be used sparingly; these
settings greatly increase the DDPRINT output size.
The ZEDCLOG parameter, can be modified when a link is open or closed.
Note:
If the node-to-node handshake indicates that the destination node
does not support zEDC data compression, the outbound payload will not be
compressed, regardless of any zEDC parameter settings on the NODE statement or
any LINK statement.
zEnterprise Data Compression (zEDC) can occur only on z/OS operating systems. Consequently, the ZEDCSLOG parameter specification should be made only on z/OS systems that support zEDC. For complete information on z/OS requirements for zEDC support, refer to IBM documentation regarding zEnterprise Data Compression (zEDC).