Resolver caching is automatically enabled and you do not
need to make parmlib or JCL changes. Unless you choose to do so, you
do not have to configure the cache; however, you can explicitly configure
resolver caching.
Before you begin
You must have already created a resolver setup file; see
The resolver setup file for more information.
Procedure
Perform the following steps to configure resolver caching:
- Specify the CACHE statement to enable system-wide caching
of Domain Name System (DNS) queries that have been resolved. System-wide caching is enabled by default, but you can explicitly
enable it by specifying this statement.
- Specify the CACHESIZE(cachesizeM)
statement to define the amount of storage, in megabytes, that can
be allocated by the resolver to manage cached records. The
default value is 200 megabytes.
Guideline: If
you set a CACHESIZE value that is too low, the resolver might repeatedly
take action to reduce cache usage. You should set the CACHESIZE value
to be at least 50 percent higher than your expected usage.
If
you specify this statement and the NOCACHE statement, the CACHESIZE
statement is ignored. For more information about cache size, see Managing the cache size and cache storage.
- Specify the MAXTTL statement to define the maximum amount
of time, in seconds, that cache entries are considered to be valid
by the resolver. The default value is the time-to-live
(TTL) value that is provided by the name server for this resource.
If you specify this statement and the NOCACHE statement, the MAXTTL
statement is ignored. For more information about cache size, see Managing the cache size and cache storage.
- Perform one of the following steps:
- If the resolver is not active, start the resolver.
- If the resolver is currently active, issue the MODIFY RESOLVER,REFRESH,SETUP=setup_file_name command
to cause the resolver to use the new settings.