Logical record cache definitions
By using logical record cache definitions, you can define the attributes of a logical record cache and manage a cache by using only z/TPF commands.
A logical record cache definition is a persistent description of a logical record cache. The cache definition specifies the name and attributes that are used to create the cache.
When you create a logical record cache definition, you must specify the name and type of the cache definition. The name of the cache definition is used as the name of the cache when you create the cache. The type of the cache definition determines whether the cache is processor unique or processor shared.
You cannot change the name or type of a cache definition after the cache definition is created. If you want to change the name or type of a cache definition, you must delete the cache definition and create it again with the new name and type specified. You cannot create a cache definition with the same name as an existing cache definition, regardless of whether the type is the same as the existing definition.
When you create a cache definition, the z/TPF system does not set any cache definition attributes. You must enter the ZCACH DEFINITION command to set certain cache definition attributes before you can create the cache. For more information about required and optional cache definition attributes, see Logical record cache definition attributes.
- The ZCACH CREATE command is entered to create a cache.
- After the ZCACH CREATE command was entered to create the cache, an IPL occurs and the z/TPF system re-creates the caches that existed on the system before the IPL.
Applications can read and update entries in a logical record cache by using the same logical record cache support functions, whether the cache was created from a cache definition or by using the newCache or tpf_newCache_ext function.