Installation guide

1.1.3 Standards Compliance
Using programming standards enhances the portability of your application.
Standard-compliant code is independent of the hardware or even the
operating system on which the application runs.
Both the ULTRIX and UWS system and the DIGITAL UNIX system have
programming environments that allow you to develop applications that
conform to the major industry standards.
The Software Product Description (SPD) for the ULTRIX product, the UWS
product, and the DIGITAL UNIX product each contain detailed lists of the
standards they support. Refer to the SPDs for this information. For
information about specific migration issues, see Chapter 7.
The DIGITAL UNIX system provides programming interfaces that are
defined in the OSF Application Environment Specification (AES) standard.
Although the AES is not a formal standard, using AES-conformant library
routines helps ensure the portability of your program between products
based on the OSF/1 operating system. The Application Environment
Specification Operating System Programming Interfaces Volume (AES/OS)
specifies programming interfaces for the operating system portion of the
OSF applications environment.
1.1.4 Shared Libraries
The DIGITAL UNIX system includes dynamic, shared libraries as part of
the programming environment. That is, the libraries contain no fixed base
addresses. When you link your application with a shared library, the
executable application does not contain the library; instead, it contains the
information needed to load the shared library at startup time and to access
the shared routines at execution time.
Because shared libraries allow several applications to use a single copy of a
library routine, they can help save disk space and memory, and improve
system performance.
For more information about shared libraries, see Section 6.6 and
Section 8.1.
1.1.5 Per-Process Open File Descriptors
Both the ULTRIX and UWS and the DIGITAL UNIX systems allow you to
configure the number of open file descriptors a process can use. By default,
the number for ULTRIX and UWS systems is 64, for DIGITAL UNIX
systems, 4096. For information about how to configure this feature, see the
System Administration manual. For information about modifying an
Introduction to Migrating from ULTRIX to DIGITAL UNIX Systems 1–3