gtpa1m09 | ACF/SNA Network Generation |
The SNA table sizes and network characteristics are defined by the SNAKEY macro and assembled offline into the SNA keypoint (CTK2). This process eliminates the need to regenerate the TPF system when the network configuration changes, simplifying installation and tuning. The value of certain selected parameters in the SNA keypoint can also be changed using the ZNKEY command. For more information about the ZNKEY command, see TPF Operations.
The SNA keypoint (CTK2) is a 4-KB record residing only in the basic subsystem (BSS). It is used to maintain the SNA network configuration and status. As a standard TPF keypoint, CTK2 has the following characteristics:
The SNA keypoint is defined by the CK2SN DSECT and is divided into three major parts:
These tables allow the initializer, CTIN, to allocate main storage and fill in the dump label table without needing to know the main storage calculations for SNA support.
Notes:
MSAT3 contains a parameter list for main storage control block requirements that are not related to SNA communications. For example, MSAT3 contains a parameter list for the main storage Transmission Control Protocol/Internet Protocol (TCP/IP) offload support and TPF Application Requester (TPFAR) control block structures.
MSAT3 allows the initializer, CTIN, to allocate main storage and fill in the dump label table without needing to know the main storage calculations for the communication-related tables.
Each parameter list entry in the MSAT contains the following:
The SNA keypoint is shipped as source code with default values supplied by the SNAKEY macro. The SIP process generates the JCL required to assemble the keypoint. Your system programmer must modify the SNAKEY macro before this assembly step to reflect your configuration. This keypoint can also be changed and reloaded at other times without rerunning the entire SIP process.
Your system programmer can change online the value of certain selected parameters in the SNA keypoint with the ZNKEY command. Changes take effect either immediately, at cycle up, or after a restart depending on the parameters that were specified for the ZNKEY command. For more information about the ZNKEY command, see TPF Operations.
Figure 1 shows how the required information is defined and passed through the various stages from SIP to the TPF online routines.