Creating TCPIP.DATA

Create a TCPIP.DATA file by copying the sample provided in SEZAINST(TCPDATA) and modifying it to suit your local conditions.

Allocate this data set with either sequential (PS) or partitioned (PO) organization, a fixed (F) or fixed block format (FB), a logical record length (LRECL) between 80 and 256, and any valid block size for a fixed block. This file can also be the file /etc/resolv.conf, or a z/OS® UNIX file that is pointed to by either the environment variable RESOLVER_CONFIG or the SYSTCPD DD in a JCL procedure. If you have a z/OS UNIX file, the maximum line length can be 256. The environment variable RESOLVER_CONFIG can also point to an MVS™ data set or PDS.

You can use any name for the TCPIP.DATA data set if you access it using the //SYSTCPD DD statement, or use ENVAR to set RESOLVER_CONFIG, in the JCL for all the servers, logon procedures, and batch jobs that execute TCP/IP functions. If you are not using the //SYSTCPD DD statement, the environment variable, or /etc/resolv.conf, then the data set name must conform to the conventions described in Configuration files for the TCP/IP stack. Another alternative is to use the well-known data set name SYS1.TCPPARMS(TCPDATA). You will eventually issue the HOMETEST command with TRACE RESOLVER activated to verify the actual data set name the system finds for TCPIP.DATA. However, because HOMETEST is an MVS sockets application, it does not use RESOLVER_CONFIG or /etc/resolv.conf in its search order. For this reason, it is recommended that /etc/resolv.conf and TCPIP.DATA contain exactly the same information or consider using the resolver GLOBALTCPIPDATA setup statement.

Rule: Because TCPIP.DATA statements might need to be read and used multiple times by the resolver, the FREE=CLOSE JCL parameter should not be used when allocating SYSTCPD. To allow TCPIP.DATA statements to be changed while still allocated for long running programs, consider using a member of an MVS partitioned data set instead of an MVS sequential data set. For these long running applications, the resolver MODIFY REFRESH command should then be used to indicate that TCPIP.DATA statements have been changed.