DLL Programmer's Guide for TNS/R Systems

Essential DLL Facility Controls
DLL Programmer’s Guide for TNS/R Systems—522203-002
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Things to Consider about the Loader
Because the search order for the linker and loader comes to D before Y (See Finding
Symbol Definitions on page 4-1), D’s Gamma masks Y’s. So without any change to the
users, all of those that formerly used old D’s Gamma will now get new D’s Gamma.
Things to Consider about the Loader
Many of the loader’s operations are automatic and driven by adequate defaults. This
subsection discusses a few of which you must be aware. For more precise control of
the loader, see Load-Time Operation on page 5-11.
The Link-Time-Defined Search Path of the Loader
The linker can run on an auxiliary system while the loader must run on the execution
target, so their search paths might necessarily be different. For example, the directory
and subvolume names are unlikely to be the same on the auxiliary and execution-
target systems. This subsection discusses how, when executing the link, you can direct
the load-time search to appropriate paths on the target system.
While the loader’s search path is similar to the linker’s, the search-path information the
linker gets from -first_L, -libvol, or -L options is not passed on to the loader.
Instead, the loader’s search path is controlled at link time by -RLD_first_L or
-RLD_L options. These are repeatable options.
The loader’s search path can also be modified at load time, as discussed in Controlling
the Loader’s Search Path at Load Time on page 5-11; however, when not augmented
at load time, the loader’s search path is:
1. The directories or subvolumes specified in a -RLD_first_L parameter
option in the linker’s command stream, where parameter is a path or paths to
a specified directory or subvolume. The -RLD_first_L option is not
required, but when used, is repeatable with different path strings.
2. The public libraries.
3. The directory or subvolume specified in a -RLD_L parameter option in the
linker’s command stream, where parameter is a path or paths to a specified
directory or subvolume. The -RLD_L option is not required but when used, is
repeatable with different path strings.
4. For OSS: /lib, /usr/lib, /usr/local/lib, /G/SYSTEM.ZDLL
For Guardian: $SYSTEM.ZDLL
Unlike the previously discussed options that guide the linker’s search, -RLD_first_L
and -RLD_L, which guide the loader’s search, allow you to specify multiple colon-
separated paths as a single argument for each option. You can also insert multiple
such options, and the linker concatenates their arguments in the order you insert them
to present the loader with a single list of colon-separated paths. The loader follows this
list in the order listed. The path names themselves cannot have colons embedded
within them.