GETHOSTBYNAME

The GETHOSTBYNAME call returns the alias name and the IPv4 IP address of a host whose domain name is specified in the call. A given TCP⁄IP host can have multiple alias names and multiple host IPv4 IP addresses.

The name resolution attempted depends on how the resolver is configured and if any local host tables exist. See z/OS Communications Server: IP Configuration Guide for information about configuring the resolver and how local host tables can be used.

Table 1. GETHOSTBYNAME call requirements
Condition	Requirement
Authorization:	Supervisor state or problem state. The PSW key must match the key in which the MVS™ application task was attached.
Dispatchable unit mode:	Task.
Cross memory mode:	PASN = HASN.
Amode:	31-bit or 24-bit. Note: See the addressability mode (Amode) considerations under CALL instruction API environmental restrictions and programming requirements.
ASC mode:	Primary address space control (ASC) mode.
Interrupt status:	Enabled for interrupts.
Locks:	Unlocked.
Control parameters:	All parameters must be addressable by the caller and in the primary address space.

Figure 1 shows an example of GETHOSTBYNAME call instructions.

Figure 1. GETHOSTBYNAME call instruction example

    WORKING-STORAGE SECTION.
        01  SOC-FUNCTION    PIC X(16)  VALUE IS 'GETHOSTBYNAME'.
        01  NAMELEN         PIC 9(8)  BINARY.
        01  NAME            PIC X(255).
        01  HOSTENT         PIC 9(8)  BINARY.
        01  RETCODE         PIC S9(8) BINARY.
 
    PROCEDURE DIVISION.
         CALL 'EZASOKET' USING SOC-FUNCTION NAMELEN NAME
                         HOSTENT RETCODE.

For equivalent PL/I and assembly language declarations, see Converting parameter descriptions.