IEHINITT (Initialize Tape) Program

IEHINITT is a system utility used to place standard volume label sets onto any number of magnetic tapes mounted on one or more tape units. They can be ISO/ANSI Version 3 or ISO/ANSI Version 4 volume label sets written in ASCII (American Standard Code for Information Interchange) or IBM standard labels written in EBCDIC.

In this topic, the term "Version 3" is used when referring to ANSI X3.27–1978, ISO 1001–1979 and FIPS 79 standards.

The term "Version 4" is used when referring to ANSI X3.27–1987 level 4 and ISO 1001–1986(E) level 4 standards.

The U.S. government followed Federal Information Processing Standard (FIPS) 79, dated October 17, 1980. It adopted the ISO/ANSI Version 3 standard as a Federal Standard. Later, it withdrew FIPS 79 and did not replace it.

IEHINITT is an APF-authorized program. This means that if another program calls it, that program must also be APF-authorized. To protect system integrity, the calling program must follow the system integrity requirements described in z/OS MVS Programming: Authorized Assembler Services Guide.

Because IEHINITT can overwrite previously labeled tapes regardless of expiration date and security protection, IBM recommends that the security administrator use PROGRAM protection with the following sequence of commands:

RDEFINE PROGRAM IEHINITT ADDMEM('SYS1.LINKLIB'//NOPADCHK) UACC(NONE)
PERMIT IEHINITT CLASS(PROGRAM) ID(users or groups who should have access) ACCESS(READ)
SETROPTS WHEN(PROGRAM) REFRESH [Omit REFRESH if you did not have this option active previously]

To further protect against overwriting the wrong tape, IEHINITT asks the operator to verify each tape mount in a non-library environment. Use of IEHINITT in a system-managed tape environment assumes that security controls have been implemented to prevent destruction of production data. SAF/RACF is invoked for authorization processing in a library environment. The level of authority required to proceed with the initialization is UPDATE for CLASS=TAPEVOL.

In addition, installation exits administered via CSVDYNEX, the dynamic exits service, are available. The use of installation exits is completely optional, but if implemented, allows an installation to review all initialization requests and indicate whether a volume should be initialized.

IEHINITT provides volume level security checking using SAF/RACF but does not invoke data set level checking. If you do not use SAF/RACF TAPEVOL profiles, extra precautions may be required when using IEHINITT in a system-managed library.

IEHINITT uses the tape label SVC (SVC number 39) to label tape volumes. The tape label SVC issues a RACROUTE in the TAPEVOL class when it is able to identify the mounted volumes' volser either by reading the tape label or from sense bytes received from the tape drive. UPDATE access to the volume is required to label the volume, or the volume must not be protected; not protected means that either there is no TAPEVOL profile or the TAPEVOL class is not active.

If you plan on using IEHINITT to re-label tape volumes (note that this excludes initializing brand new volumes) and you want to provide protection for labelling and control which users can do this, you should have the TAPEVOL class active and define TAPEVOL profiles. When you use the TAPEAUTHDSN DEVSUPxx option, or use RACF TAPEDSN to protect tape data sets you can define one or more generic TAPEVOL profiles to cover all volumes.

If you use the DFSMSrmm EDGINERS tape labelling and erasing utility you do not need to have the TAPEVOL class active. DFSMSrmm controls who can use the EDGINERS utility and you can only label or erase volumes which are either new to DFSMSrmm or have the INIT or ERASE action pending.

Note: As an alternative to IEHINITT, consider using the EDGINERS utility as described in Using DFSMSrmm. EDGINERS checks security and volume ownership and provides auditing; IEHINITT does not.

Each volume label set created by the program contains:

A standard volume label with a serial number you specify, owner identification, and a blank security byte. ISO/ANSI
Version 3 and Version 4 labels may contain an access code other than an ASCII space by using the ACCESS keyword. A label conforming to the ISO/ANSI Version 3 standard will be created if a Version 3 label is requested. A label conforming to the Version 4 standard will be constructed if a Version 4 label is requested.

A complete description of IBM standard volume labels and Version 3 and Version 4 volume labels is in z/OS DFSMS Using Magnetic Tapes .
An 80-byte dummy header label. For IBM standard labels, this record consists of the characters "HDR1" followed by character zeros. For Version 3 or Version 4 labels, this record consists of the characters "HDR1" followed by character zeros in the remaining positions, with the exception of:
- Position 54, which will contain an ASCII space;
- A "1" in the file section, file sequence, and generation number fields;
- A leading space in the creation and expiration date fields;
- A system code of "IBMZLA", which identifies the operating system creating the label, followed by 14 spaces.
A tape mark.

When a labeled tape is subsequently used as a receiving volume, the OPEN or EOV function:

Rewrites the volume label.
Rewrites the dummy HDR1 record created by IEHINITT with operating system data, device-dependent information, and data set information.
Writes HDR2 record, containing data set characteristics.
Writes user header labels if the user program provides exits to user label routines.
Writes a tape mark.
Positions the volume for the user program to write data.

Note for Version 3 and Version 4 Tape Labels:

For Version 3 there is no accessibility code checking done during IEHINITT processing, other than checking for uppercase A through Z in the ACCESS keyword. Therefore, it is possible to create a tape with a volume access code that the receiving operating system will not recognize. In such a situation, the tape would have to be reinitialized to contain an acceptable access code.

The set of valid Version 3 characters is:

  upper case A--Z, numeric 0--9, and the special characters
  | " % & ' ( ) * + , - . / : ; < = > ? space

The set of valid Version 4 characters is:

  upper case A--Z, numeric 0--9, and the special characters
  | " % & ' ( ) * + , - . / : ; < = > ? _ space

The only difference between the two lists of special characters is the _ (underscore).

If a Version 3 or Version 4 volume is initialized only with IEHINITT, the labels produced do not frame an empty (null) data set as required for interchange. In order to produce label symmetry described by the ISO/ANSI standards, at least a minimal Open/Close sequence must be processed. For example, a volume initialized previously with IEHINITT will result in label symmetry if the data set utility IEBGENER is used before the volume leaves the system for interchange, as follows:

   //STEP1    EXEC  PGM=IEBGENER
   //SYSPRINT DD    DUMMY
   //SYSUT1   DD    DUMMY,DCB=(RECFM=F,BLKSIZE=80,LRECL=80)
   //SYSUT2   DD    DSN=DUMMY,UNIT=(tape),LABEL=(,AL),DISP=OLD,
   //               DCB=(RECFM=F,BLKSIZE=80,LRECL=80),VOL=SER=volser
   //SYSIN    DD    DUMMY

Related reading :

For more information, see z/OS DFSMS Installation Exits.
For a information about volume labels, see z/OS DFSMS Using Magnetic Tapes .