Space calculations
Estimate the amount of space needed in your global catalog to keypoint installed resource definitions, table entries, and control blocks. Each global catalog record has a 52-byte key. Each entry is one VSAM record, and the records for each type of table have different keys.
You must regularly review your space usage to ensure that extents are not running too close to the limit for your environment. Use the sizes specified in Table 1 to estimate the amount of space needed in your global catalog.
The space requirements for a VSAM KSDS such as DFHGCD can vary for different CICS cold starts. They can vary when no changes have been made to the CICS definitions that are going to be stored on the VSAM KSDS, because VSAM uses the space in the data set differently depending on whether the data set has just initialized or has data from a previous run of CICS. CICS calls VSAM to perform sequential writes. VSAM honors the freespacevalue specified on the data set's definition if the keys of the records being added sequentially are higher than the highest existing key. However, if the data set contains existing records with a higher key than the ones being inserted, the freespace value is only honored after a CI split has occurred.
The size of the index portion of the data set can also vary depending on the number of CI and CA splits that have occurred. The size affects the index sequence set.
When you are initializing the global catalog, you can use the COLD_COPY parameter; for example, SET_AUTO_START=AUTOCOLD,COLD_COPY. The cold copy creates a reduced copy of the global catalog data set, which improves the performance of the cold start. The CI splits cease after the first cold start and the data set will not expand into additional extents. Alternatively, you can reorganize or reinitialize the data set from time to time.
| Installed definition, table entry, or control block | Number of bytes per entry | Size in previous release if different |
|---|---|---|
| Installed ATOMSERVICE definition | 660 bytes | |
| Installed BUNDLE definition 1 | 300 bytes up to 800 bytes approximately | |
| Installed CONNECTION definition | 528 bytes | 440 bytes |
| Installed CORBASERVER definition | 1304 bytes | 1216 bytes |
| Installed DB2CONN definition | 1548 bytes | 1460 bytes |
| Installed DB2ENTRY definition | 332 bytes | 244 bytes |
| Installed DB2TRAN definition | 160 bytes | 62 bytes |
| Installed DJAR definition | 432 bytes | 344 bytes |
| Installed DOCTEMPLATE definition | 284 bytes | 196 bytes |
| Installed ENQMODEL definition | 152 bytes | 64 bytes |
| Installed EVENTBINDING and CAPTURESPEC definitions 2 | 4000 bytes approximately | |
| Installed extrapartition queue definition | 392 bytes | 296 bytes |
| Installed FILE definition | 588 bytes | 500 bytes |
| Installed indirect queue definition | 180 bytes | 92 bytes |
| Installed intrapartition queues definition | 328 bytes | 240 bytes |
| Installed IPCONN definition | 402 bytes | 312 bytes |
| Installed JOURNALMODEL definition | 168 bytes | 80 bytes |
| Installed JVM Program definition | 168 bytes up to 307 bytes | 80 bytes up to 219 bytes |
| Installed JVMSERVER definition | 146 bytes | |
| Installed LIBRARY definition | 852 bytes | 764 bytes |
| Installed MQCONN definition | 620 bytes | |
| Installed MQINI definition | 212 bytes | |
| Installed PARTNER definition | 148 bytes | 124 bytes |
| Installed PIPELINE definition | 1500 bytes | 1412 bytes |
| Installed PROCESSTYPE definition | 148 bytes | 60 bytes |
| Installed PROFILE definition | 158 bytes | 70 bytes |
| Installed PROGRAM definition | 168 bytes | 44 bytes |
| Installed REQUESTMODEL definition | 226 bytes | 138 bytes |
| Installed remote queue definition | 172 bytes | 84 bytes |
| Installed TCPIPSERVICE definition | 924 bytes | 580 bytes |
| Installed model TERMINAL definitions 3 | 634 bytes | 610 bytes |
| Installed TRANCLASS definitions | 124 bytes | 36 bytes |
| Installed TRANSACTION definitions (without TPNAME) | 244 bytes | 140 bytes |
| Installed TRANSACTION definitions (with TPNAME or XTPNAME) | 388 bytes | 204 bytes |
| Installed TSMODEL definition | 236 bytes | 148 bytes |
| Installed TYPETERM definitions 3 | 634 bytes | 610 bytes |
| Installed VSAM file (or data table) definition | 312 bytes | 288 bytes |
| Installed URIMAP definition | 1316 bytes | 1220 bytes |
| Installed WEBSERVICE definition | 1040 bytes | 936 bytes |
| BDAM file control table entry (FCT) | 284 bytes | 146 bytes |
| BDAM data control blocks | 156 bytes | 132 bytes |
| VSAM LSR share control blocks 4 | 1224 bytes | 1184 bytes |
| Data set names (JCL or dynamically allocated) 5 | 96 bytes | 72 bytes |
| Data set name blocks | 194 bytes | 170 bytes |
| Eventprocess status | 89 bytes | |
| File control recovery blocks 6 | 149 bytes | 125 bytes |
| Terminal control table entry (TCT) | 1552 bytes approximately | 1500 bytes approximately |
| Dump table entry | 100 bytes | 76 bytes |
| Interval control element (ICE) | 120 bytes | 96 bytes |
| Automatic initiator descriptor (AID) | 120 bytes | 96 bytes |
| Deferred work element (DWE) 7 | 132 bytes | 108 bytes |
| Installed journal | 111 bytes | 88 bytes |
| Recovery manager remote names | 158 bytes | 134 bytes |
| Transient data destination record | 70 bytes | 46 bytes |
| Transient data destination auxiliary record | 58 bytes | 34 bytes |
| Loader program definitions | 68 bytes | 44 bytes |
| Session TCTTEs | 918 bytes | 894 bytes |
| Log streams | 112 bytes | 88 bytes |
| Uri virtual hosts | 180 bytes | 156 bytes |
Notes
- The size of a bundle catalog record depends on the number of parts that are included in the bundle, the size of the bundle directory, and the length of the scope. The minimum size for a bundle with no scope and small directory is approximately 300 bytes. However, with a scope and large directory, the number of bytes can increase to 800. For each bundle part, the size can also range from 300 to 800 bytes.
- The size of an event binding catalog record depends on the number of capture specifications in the event binding and the number of filters and capture data items in each capture specification. If required, you might have multiple catalog records for each event binding.
- The TYPETERM and model TERMINAL definitions are present if you are using autoinstall. They are stored directly in the global catalog when the definitions are installed, either by a CEDA transaction, or as members of a group installed through a group list. For example, if you start CICS with the startup parameter GRPLIST=DFHLIST, the CICS-supplied TYPETERM and model terminal definitions, defined in the groups DFHTERM and DFHTYPE, are recorded in the global catalog. Allocate space in your calculations for all autoinstall resources installed in your CICS region.
- One for each LSR pool; that is, 8.
- If you open a VSAM path, you get two of these; for BDAM or VSAM base data sets you get one.
- You will have these if you use the VSAM RLS SHCDS option NONRLSUPDATEPERMITTED. In this case, for each data set for which you have specified NONRLSUPDATEPERMITTED, you can have an upper limit. This limit is the number of different file names through which you access the data set multiplied by the number of tasks that update the data set. You will typically have only a few, if any, of these control blocks.
- The value given is for a DWE chained off an LU6.1 session or an APPC session.