For z/OS Release 2, UNIX System Services offers improved application flexibility, new tools for managing e-business, and greater ease of use. Highlights include:

Improved application flexibility: Enhanced ASCII functionality

Enhanced ASCII functionality makes it easier to port internationalized applications developed on (or for) ASCII platforms to z/OS platforms, by providing conversion from ASCII to EBCDIC and from EBCDIC to ASCII.

Enhanced ASCII introduces:

  • A file tagging mechanism, which allows programmers to tag files with a file attribute that describes the contents of the file. The file tag contains a Coded Character Set Identifier (CCSID) that identifies the character set of the text data within the file, and indicates whether the file is eligible for automatic conversion.
  • Support for automatic data conversion between character sets when the CCSIDs of a program and a file it is reading or writing to are different.

Enhanced ASCII support applies only to z/OS UNIX files; it does not apply to MVS files, even if they can be accessed by z/OS UNIX. For more information about the limitations of Enhanced ASCII, see z/OS C/C++ Programming Guide.

Specific changes in support of Enhanced ASCII include:

  • A new statement in the BPXPRMxx parmlib member, AUTOCVT(ON|OFF), globally enables and disables the automatic text conversion of I/O data between code sets. AUTOCVT can be turned on or off with the SETOMVS and SET OMVS operator commands. Automatic conversion can also be overridden by individual programs at a thread level using flags in the thread control block.
  • The MOUNT statement in BPXPRMxx has a new keyword, TAG, which specifies whether files should be converted during reading and writing.
  • The TSO/E MOUNT command has a new operand, TAG(NOTEXT|TEXT,ccsid) to support file tagging.
  • Shell commands are added or changed to support file tagging and automatic file conversion:
    • A new shell command, chtag, assigns, changes, and removes the file tag on existing files.
    • The new -T option on the cksum shell command enables the automatic conversion of tagged files.
    • The new -B option on the cmp shell command disables the automatic conversion of tagged files.
    • The new tag option on the automount command specifies whether file tags for untagged files in the mounted file systems are to be implicitly set.
    • New options on the cp, df, file, find, head, icnov, localedef, ls, mount, mv, od, pack, pax, strings, tail, tcsh, and test shell commands support file tagging and/or automatic file conversion.
  • Two new environment variables are added to support file tagging and automatic file conversion. BPXK_AUTOCVT enables the conversion of data between EBCDIC and ASCII code sets, and _BPXK_CCSIDS identifies an EBCDIC or ASCII pair of corresponding CCSIDs. (Only one pair is supported with this release: EBCDIC 1047 and ISO-8859-1.)
  • New shell variables (_TAG_REDIR_IN, _TAG_REDIR_OUT, and _TAG_REDIR_ERROR) control the conversion of untagged files. (See the descriptions of the sh and tcsh commands in z/OS UNIX System Services Command Reference.)
  • The BPX1FCT callable service controls the automatic conversion of file data with two new arguments. F_SETTAG sets the file tag, and F_CONTROL_CVT controls automatic file conversion.

New tools for managing e-business

  • HFS control
    The new FACILITY class profile BPX.DAEMON.HFSCTL enforces program control for HFS programs only. When users are given permission to this profile, z/OS UNIX bypasses program control rules for programs loaded from MVS libraries, but enforces the rules for HFS programs.
  • Soft shutdown for mounted file systems
    This enhancement allows files systems to be unmounted without the loss of data. A new keyword on the MODIFY operator command, SHUTDOWN=FILESYS, specifies that all active file systems on this system are to be unmounted and the data synched to disk. In a sysplex environment, AUTOMOVE(YES) file systems that are owned by this system are moved to another system.
  • A new file system, zFS, which can be used in addition to HFS
    zServer File System (zFS) is a new file system for z/OS UNIX System Services that can improve performance for many applications, especially those that access very large sequential files. For more information about zFS, see Distributed File Service zFS Administration.

Greater ease of use

  • Support for the TCP/IP Services resolver enhancement
    The TCP/IP Services resolver enhancement provides common functionality across native MVS and z/OS UNIX environments. The key functions for the various z/OS resolver libraries, which are used by TCP/IP Services applications for name-to-address or address-to-name resolution, are consolidated into a new, single resolver component.
    • A new BPXPRMxx statement, RESOLVER_PROC, specifies the name of a cataloged procedure in SYS1.PROCLIB that will be used to start the resolver address space during z/OS UNIX initialization.
    • DISPLAY OMVS,O displays the RESOLVER_PROC specification.
    • Two new callable services, gethostbyname(BPX1GHN) and gethostbyaddr (BPX1GHA), provide access to the system resolver functions.
  • Enhancement to uname utility for OS/390 to z/OS compatibility
    The uname utility has a new option that allows for continued support of the name OS/390 within the uname() field.


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