IBM Support

Resolver Calls Fail Even Though Input Files Are Properly Defined

Troubleshooting


Problem

Issuing a Resolver call (such as gethostbyname(), gethostbyaddr(), getnameinfo(), or getaddrinfo()) fails with an indication that the name or address could not be found. The /etc/resolv.conf file appears to be configured correctly.

Symptom

  • The UNIX file is accessible by using the OMVS prompt, and can be viewed by any user.

  • Copying the file to the MVS data set name used in the Resolver search order causes the call to work.

  • There are no SAF (RACF) errors recorded for these access attempts.

  • When a SYSTCPRE CTRACE of the attempt is collected, a Dynamic Allocation Failure record is shown for the file:

    EMRG      FILEIO    00070002  09:35:31.871742  !Dynamic Allocation Failed
    ASID...001E       TCB...009EA1F8        JOBN...TCPIP
    MODID...EZBRECMR  CID...00000000        REG14..0B8D3604
      ADDR...7EFF6FE0 LEN...00000004        DynAlloc Return Code
    000000 00000004                            |....            |
      ADDR...7EFF71C0 LEN...00000014        SVC99 Request Block
    000000 14016000 04D00000 7EFF7690 00000000 |..-.....=.......|
    000010 00000000                            |....            |
      ADDR...7EFF7690 LEN...0000000C        SVC99 Text Unit List
    000000 7EFF76C0 7EFF72E0 FEFF72EA          |=...=.......    |
      ADDR...7EFF76C0 LEN...00000016        SVC99 Text Unit
    000000 80170001 00106185 A3836199 85A29693 |....../etc/resol|
    000010 A54B8396 9586                       |v.conf          |
      ADDR...7EFF72E0 LEN...0000000A        SVC99 Text Unit
    000000 80180001 00040000 0002              |..........      |
      ADDR...7EFF72EA LEN...0000000E        SVC99 Text Unit
    000000 00550001 00080000 00000000 0000     |..............  |
      ADDR...00000000 LEN...00000000        SVC99 Text Unit
      ADDR...00000000 LEN...00000000        SVC99 Text Unit

  • Note the DYNALLOC Reason Code shown at +4 in the SVC99 Request Block. Code 04D0 indicates a problem with the SMS subsystem.

This error can also occur with accesses to the /etc/hosts file. Similar problems can be encountered with other calls, even though the associated UNIX file is defined:

  • getprotobyname() or getprotobynumber(), which use /etc/protocol
  • getservbyname() or getservbyport(), which use /etc/services

Cause

The SMS address space is not running on this LPAR. DYNALLOC references to UNIX files (equivalent to the PATH specification on the JCL DD statement) fail without that subsystem active.

Diagnosing The Problem

Resolving The Problem

Configure and start the SMS subsystem.

[{"Type":"MASTER","Line of Business":{"code":"LOB35","label":"Mainframe SW"},"Business Unit":{"code":"BU054","label":"Systems w\/TPS"},"Product":{"code":"SSSN3L","label":"z\/OS Communications Server"},"ARM Category":[{"code":"a8m0z0000000AgDAAU","label":"z\/OS Comm Server->TCPIP->RESOLVER->Resolver search order issue"}],"ARM Case Number":"","Platform":[{"code":"PF035","label":"z\/OS"}],"Version":"All Versions"}]

Document Information

Modified date:
03 July 2021

UID

swg21294398

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