The STRUCTURECACHE command is used to set and display values for caches maintained by the system for a number of data structures.
Syntax
Explanation
All forms of the STRUCTURECACHE command generate a display of the current parameter settings and current data statistics for all four types of cache.
STRUCTURECACHE DIRECTORY <integer>
Sets the size of the disk directory cache. This cache holds blocks of the data structure used by the system to locate disk files according to title. A value of zero (0) disables this cache. The default value is 1024 blocks, and the maximum value is 1,048,575 blocks.
STRUCTURECACHE HEADERS <integer>
Sets the size of the disk file header cache. This cache retains the disk file headers of files that have been recently used but that are currently not in use. A value of zero (0) disables this cache. The default value is 1024 headers, and the maximum value is 524,287 headers.
STRUCTURECACHE CODESTACKS <integer>,<integer>
Sets values for the code stack cache. This cache retains a number of code stacks that have been recently used but that are currently not in use. The first parameter specifies the size of the cache, and the second parameter specifies the time limit for the cache to retain a code stack. Setting either value to zero (0) disables the cache. The default size value is 256 stacks, and the time default value is 60 seconds. The minimum size is 256 stacks and the maximum size is 1,048,575 stacks. The minimum time is 60 seconds and the maximum time limit is 100,000,000 seconds.
| Note: | You can use the RP (Resident Program) command to retain code stacks with no users. |
STRUCTURECACHE USERDATAFILE <integer>
Sets the size of the SYSTEM/USERDATAFILE cache. This cache contains entries of the data structure used by the system to record usercodes and their associated attributes. Setting the value to zero (0) disables the cache. The default value is 1024 entries, and the maximum value is 1,048,575 entries.
Examples
Example 1
The following example sets a new value for the size of the code stack cache and uses the default value for the time limit:
STRUCTURECACHE CODESTACKS 256, 60
Example 2
The following example displays all the information for the caches maintained by the system for the data structures. The information displayed when the command is executed is included in this example.
STRUCTURECACHE
Disk Directory Cache
Size = 1,048,575 blocks (10,049,574 words in use)
current rate (per sec) since last Halt/ Load
read hits/reads 22.73/22.73 = 100% 990602/993412 = 100%
read hits/reads+writes 22.73/22.73 = 100% 990602/1.005E6 = 99%
reads/reads+writes 22.73/22.73 = 100% 993412/1.005E6 = 99%
Disk File Header Cache
Size = 1,024 headers (246,834 words in use)
current rate (per sec) since last Halt/Load
already open/requests 0.39/27.58 = 1% 4437/629596 = 1%
cache hits/requests 27.19/27.58 = 99% 296959/629596 = 47%
misses/requests 0.00/27.58 = 0% 328200/629596 = 52%
Code Stack Cache
Size = 256 stacks (598,990 words in use)
Time limit = 10,000 seconds
current rate (per sec) since last Halt/Load
already running/requests 0.19/0.58 = 33% 859/1644 = 52%
cache hits/requests 0.10/0.58 = 17% 166/1644 = 10%
misses/requests 0.29/0.58 = 50% 619/1644 = 38%
SYSTEM/USERDATAFILE Cache
Size = 1,024 entries (18,535 words in use)
current rate (per sec) since last Halt/Load
read hits/reads 3.51/3.71 = 95% 8631/8744 = 99%
read hits/reads+writes 3.51/3.71 = 95% 8631/8759 = 99%
reads/reads+writes 3.71/3.71 =100% 8744/8759 =100%
