n statement, it saves this value as the stack's host name.
If a TCPIP.DATA HOSTNAME configuration statement is not read, the TCP/IP stack searches for the Virtual Machine Communication Facility (VMCF) node name from VMCF and uses its node name as the stack's host name.
Note: VMCF should be running before any TCP/IP stacks are started.
If VMCF is not running when the TCP/IP stack is started, the TCP/IP stack's host name is determined by the release of the operating environment.
For releases before z/OS 1.2, the stack's host name is set to a NULL string.
For z/OS 1.2 and later releases, the stack's host name is set to the CVTSNAME, which is the SYSNAME=value in IEASYSnn that was used when the system was started.
Multiple Host Names in a Single File
As an option, you can insert a prefix system_name in TCPIP.DATA configuration statements. Using prefixes enables you to configure multiple hosts in a single TCPIP.DATA data set. The system_name prefix is matched against the system name that the TCP/IP stack is started under. The system_name is identical to the VMCF node name. The TCP/IP stack reads and processes the TCPIP.DATA configuration statements in the order that they appear in the data set.
This example shows a HOSTNAME statement in a TPCIP.DATA data set:
The system_name is specified in the first column; the associated host_name is specified in the final column.
A TCP/IP stack that was started on the system named SDCMVS would set its host name to PROD. A TCP/IP stack that started on the system named SDCESA would set its host name to TEST. A TCP/IP stack that started on the system named S390DEVA would set its host name to DEV.
The following rules are used to process HOSTNAME statements:
If the system_name prefix does not match a host name, the configuration statement is ignored.
If the system_name prefix is not located, the configuration statement is applied to all hosts.
If the system_name matches a host name, the associated configuration statement is applied to that host.
The final configuration statement that matches a system_name remains in effect.
A HOSTNAME statement is ignored under these conditions:
the system_name prefix did not match the VMCF node name
VMCF is unavailable
The system name does not match the MVS name of the system that the TCP/IP stack started under.
Therefore, it is critical that VMCF is running before any TCP/IP stacks are started.
IBM System Name Considerations
The VMCF node name is used as the system_name prefix when processing IBM TCPIP.DATA configuration statements. The VMCF can be configured in two ways:
as a restartable subsystem
If you have configured VMCF as a restartable subsystem, the node name is obtained from the value of the P= parameter in the EZAZSSI started procedure.
as a non-restartable subsystem
If you configured VMCF as a non-restartable subsystem, the node name is specified in the IEFSSNnn member of parmlib.
Note: IBM recommends that the MVS system name be used for the VMCF node name specification.
For details about configuring VMCF, see References.
|TCP/IP Stack Configuration Files|
When a TCP/IP stack is started, the TCP/IP stack reads one or more configuration files that contain statements that define its default behavior. Here are the configuration files:
The following PROFILE.TCPIP statements can restrict the ports that SAS servers can use:
reserves ports for server tasks. The PORT statement specifies only the job names and PROC names that are allowed access to the port.
is the same as PORT parameter but for a range of ports.
defines a list of user IDs that are prohibited from using TCP/IP.
restricts the use of ports 1 to 1023 to specific job names or PROC names that are specified in the PORT or the PORTRANGE statement.
The search order that is used by the IBM TCP/IP stack to locate PROFILE.TCPIP involves both explicit and dynamic data-set allocation, as follows:
//PROFILE DD DSN=
Note: IBM recommends explicitly specifying the PROFILE DD statement in the TCPIPROC JCL. When the PROFILE DD statement is specified, no dynamic allocation is performed.
SAS does not access the 