ECI performance considerations when using COMMAREAs

The performance of ECI might be affected by the amount of data transmitted over the network in the COMMAREA between the client application and the CICS® server.

To reduce the number of bytes transmitted over network protocols between the Gateway daemon and the CICS server the CICS Transaction Gateway removes trailing nulls from the COMMAREA before transmission and restores them again after transmission, this is referred to as null stripping. Null stripping is transparent to client application programs which always see the full-size COMMAREA.

The CICS server adds trailing nulls to the data received to extend it to the length specified in Commarea_Length so that the server program always receives a full COMMAREA. The CICS server also performs null stripping before transmitting the COMMAREA back over the network.

To reduce the number of bytes transmitted between a Client application and the Gateway daemon, functions are provided to set the length of data in the COMMAREA that is to flowed to the CICS server, COMMAREA outbound length, and to set the length of COMMAREA data returned from the Gateway daemon to the client application, COMMAREA inbound length.

For JEE applications:
  • the outbound COMMAREA length is set automatically by the CICS Transaction Gateway to remove trailing nulls
  • use the setReplyLength and getReplyLength methods of the ECIInteractionSpec for the inbound COMMAREA length
For Java Client applications use the following methods:
  • setCommareaOutboundLength
  • setCommareaInboundLength
  • getInboundDataLength
For ECI v2 applications use the CTG_ECI_PARMS parameter block fields:
  • commarea_outbound_length
  • commarea_inbound_length
For .NET applications use the EciRequest class fields:
  • CommareaInboundLength
  • CommareaOutboundLength
Figure 1. COMMAREA data flow optimizations using IPIC, TCP/IP or SNA

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Timestamp icon Last updated: Tuesday, 19 November 2013


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