Improving Performance for TCP/IP Transfers with CA XCOM for z/OS.

Document ID : KB000009377
Last Modified Date : 14/02/2018
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PACK=LENGTH with MAXPACK=31744 should be selected when using CA XCOM Data Transport over TCP/IP.


Set the following parameters to improve throughput for TCP/IP transfers:

  1. Set MAXPACK=31744 in the default table or config member or destination member or use the largest packet size that your network can handle.
  2. Specify PACK=LENGTH and RECSEP=NO in the SYSIN01 parameters or the destination member for the partner to improve performance. If you are using the panels to submit the transfer,
Record Separators (Y/N)---: Y
Pack Data Records(N/C/L): L
    on the

    Send MVS File To Another System


      In most cases, this can cause dramatic performance improvements. These performance improvements are obtained because you are changing from sending a record at a time to sending 31K packed buffers. PACK=LENGTH supports both text and binary files.

      Here is a summary of the information about PACK=LENGTH based on the documentation in the CA XCOM Data Transport User's Documentation- see link below.


      Specifies that the records are to be packed into fixed-size data transfer blocks. Each record begins with a 2-byte long prefix that indicates the length of the record and determines how many records can be packed into a block. The default block size is 2K but it can be increased to 31K by using the MAXPACK parameter in the CA XCOM Data Transport Default Options Table or in the CA XCOM Data Transport control library member. When transferring a text file to a partner that supports record separators (for example, CRLF (0D0A) on NT and LF (0A) on UNIX), record separators will be inserted. No separators are inserted in binary files transferred with PACK=LENGTH.


      If PACK=LENGTH is coded, then you must also code RECSEP=NO since PACK=LENGTH processing inserts record separators during processing. You will receive an error message if you specify RECSEP=YES with PACK=LENGTH. Platforms that support PACK=LENGTH are IBM's AS/400 i5/OS, Windows systems, UNIX, Linux-based systems and z/OS systems. See the appropriate documentation for the platform to see if this value is supported.

      Large packing is not turned on until you actually specify PACK=LENGTH and RECSEP=NO in the SYSIN01 or panel parameters or put these values in a destination member for the partner and enable it.

      Packing is not dependent on the block size. It is dependent on the LRECL. The smaller the LRECL and the larger the packing size, the better the performance.

      Additional Information:

      Online documentation for CA XCOM Data Transport for z/OS 12.0