Data Cache Memory

When the SAP ASE server is first installed, all data cache memory is assigned to the logical page size pool of the cache named default data cache. The default data cache is used by all objects that are not explicitly bound to a data cache with sp_bindcache or with databases that are not bound to a cache.

When you create data caches, the memory allocation is validated against max memory. Memory for caches is allocated out of the memory allocated to the SAP ASE server with the total logical_memory configuration parameter. To increase the amount of space available for caches, increase total logical memory, or decrease other configuration settings that use memory. If the sum of total logical memory and additional memory requested is greater than max memory, then the SAP ASE server issues and error and does not perform the changes.

The default cache is used for all objects, including system tables, that are not bound to another cache, and is the only cache used during recovery. For more information, see the System Administration Guide.
A data cache requires a small percentage of overhead for structures that manage the cache. All cache overhead is taken from free memory. To see the amount of overhead required for a specific size of cache, use sp_helpcache, giving the size:
```
sp_helpcache "200M"
```
```
10.38Mb of overhead memory will be needed to manage
a cache of size 200M
```
This is only an estimate of the overhead. The actual overhead may be larger because of runtime issues.