Mode configuration parameters

The following parameters are required for mode configuration:

Name

The name of the mode you are defining. The mode name is a string of 1-8 characters.

APPC applications that use this mode, including both local and remote applications, may also use this name, so check the name with your application developer (or refer to your product documentation for a third-party application).

COS name

The name of the class of service for this mode. The name is a string of 1-8 characters. Usually you can simply specify #INTER for modes used for interactive data exchange and #BATCH for modes used for bulk data transfer.

This field applies only to a network node.

If you do not know what value to specify, consult your SNA network planner.

Session limits

Use the following fields to specify session limits:

Initial session limit

The maximum number of sessions (up to the maximum session limit) that a pair of LUs can have using this mode, unless a different maximum is negotiated using CNOS.

Normally, use the value 8 for this field. If you are in doubt, consult your SNA network planner or APPC application developer (or for a third-party application, the product documentation).

Maximum session limit

The maximum number of sessions (up to 32,767) permitted between a pair of LUs using this mode, even with CNOS negotiation.

This field is usually set to the same value as the initial session limit. If you are in doubt, consult your SNA network planner or APPC application developer (or for a third-party application, the product documentation).

Minimum contention winner sessions

The number of sessions (up to the session limit) that CS/AIX must reserve for use by the local LU as the contention winner.

This field can usually safely be set to 0, but if you are not sure, consult your SNA network planner.

The sum of the minimum contention winner sessions and the minimum contention loser sessions must not exceed the initial session limit.

Minimum contention loser sessions

The minimum number of sessions that CS/AIX must reserve for use by the local LU as the contention loser. Together with the value in the Minimum contention winner sessions field, this value determines how to resolve contention for a session.

This can usually safely be set to 0, but if you are not sure, consult your SNA network planner.

The sum of the minimum contention winner sessions and the minimum contention loser sessions must not exceed the initial session limit.

Auto-activated sessions

The number of sessions (up to the minimum contention winner count) that are automatically activated after CNOS negotiation has taken place for a session between a local LU and partner LU using this mode. Specifying a value for this field enables an LU that uses this mode to start sessions automatically in response to a request from a TP for a conversation to be allocated immediately.

Receive pacing window

Use these fields to specify how many RUs can be received before an SNA pacing response is sent:

Initial window size

The initial setting for the number of request units (RUs) that the local LU can receive before it must send a pacing response to the remote LU. This can be safely set to 4.

Setting it higher can improve performance in some circumstances, but doing so also increases memory usage.

Maximum window size

The maximum number of request units (RUs) that the local LU can receive before it must send a pacing response to the remote LU.

This value is optional. If it is not supplied, the maximum receive pacing window is unlimited. If a value is supplied, it is used to limit the size of the receive pacing window for adaptive pacing. If adaptive pacing is not used, this value is ignored.

The pacing window can be from 0 through 32767 bytes. A value of 0 specifies an unlimited window.

If the adjacent node supports only fixed pacing, these values determine the fixed-pacing window size; but the adjacent node can still set a window size through negotiation. If the adjacent node uses adaptive pacing, these values set the initial window size. For more information about performance and tuning, refer to the IBM Communications Server web pages at https://www.ibm.com/products/communications-server-for-data-center.

Specify timeout

Select this option if you want to specify the number of seconds (0 - 65535) that an LU 6.2 session using this mode must be inactive before it can time out. Changing this value affects only sessions that are activated using this definition (not sessions that are already active).

If you use a value of 0, sessions are timed out as soon as they become free.

Restrict maximum RU size

Select this option if you want to specify the maximum RU size, which determines how much data is buffered before being sent to the partner LU.

The upper limit can be from 256 through 62440 bytes. You can safely set the upper limit to 1024 bytes. Setting it higher can improve performance in some circumstances, but doing so also increases memory usage.

The lower limit can be 0 or a value from 256 through the upper limit you specify.

If the value in this field is different from the RU size defined for the remote node, the size used for a session with that node can be negotiated to establish an appropriate RU size for the session. The actual value cannot be lower than the lower limit field.

These numbers, together with the send and receive pacing values, can be used to tune the session-level throughput between the local and partner LUs. If you do not know what values to use, start with the default values and adjust them as needed to maximize throughput. For more information about performance and tuning, refer to the IBM Communications Server web pages at https://www.ibm.com/products/communications-server-for-data-center.

Compression supported

Whether data compression is supported for sessions using this mode. If you do not set this option, compression will not be used.

If you set this option, you can specify the maximum compression levels to be used for inbound data and for outbound data. These are separate options so that you can specify different levels for the two directions, or use compression in one direction but not in the other. In each direction, you can select None for no compression, or one of the values RLE (minimum compression), LZ9, or LZ10 (maximum compression).

Reset to SNA defined values

If you are modifying a standard mode using the Motif dialog, you can click on this button to reset the values of the mode parameters to the SNA-defined values.