Avoiding Socket Errors Sending Transfers to CA XCOM Data Transport for Windows.

Document ID : KB000022955
Last Modified Date : 14/02/2018
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Question: 

How to avoid socket errors on transfers to CA XCOM for Windows and increase performance?

Answer: 

Increasing the Maximum Clients Range parameter for CA XCOM for Windows may increase the performance when transferring many simultaneous files to Windows.

Description of the Maximum Client Range Parameter

The Maximum Clients Range value controls the maximum number of incoming (remote) transfers which can be handled by the CA XCOM TCP/IP listener function (caxcgsvr.exe) at one time. The CA XCOM TCP/IP listener function handles incoming transfers until the CA XCOM transaction program (xcomtcp) starts and takes control of the transfer.

How it Works

If the number of incoming (remote) transfers which are starting at one time exceeds the Maximum Clients Range value, then the listener waits while transfers in progress run through to completion. The listener will continue once one of the previously started transaction programs has been initialized.

How to Set this Parameter

The default parameter value for Maximum Clients Range is 16. CA XCOM allocates a 32K block of storage for each Maximum Clients buffer. In general, Maximum Clients Range should be set to a number slightly more than half the number of simultaneous transfers that are incoming to the Windows box. You should take into consideration the total number of simultaneous transfers that may be coming in from all the remote partners. The Maximum Clients Range parameter does not indicate the maximum number of simultaneous transfers that may be active to the Windows, but specifies a buffering parameter. It allows the CA XCOM TCP/IP listener on Windows to buffer transfers coming in and holds them for the XCOM transaction program until it can process the transfer.

This parameter is only set in the XCOM GUI.
On Windows, in the XCOM GUI, select:

Tools                                            Global Parameters                                TCP/IP tab

Change the parameter in the Maximum Clients Range box to the desired value and click apply. Recycle xcomd.

For example:

The CA XCOM Data Transport for z/OS is sending 40 simultaneous transfers to Windows. The Maximum Clients Range parameter should be set to a value more than half, such as 25.