There are no restrictions on the data set names you choose for CICS® data sets, other than MVS™ constraints. In the examples in this book, CICSTS31.CICS is used as the high-level qualifier, and the DD name as the lowest level. If you are running multiple CICS regions, and especially if you are running CICS with XRF, you can use the CICS APPLID as a second level qualifier.
You are recommended to use the CTGI naming convention, as described in the OS/390® Parallel Sysplex® Application Migration manual, GC28-1863.4
For example, if CICSHTH1 is the APPLID, the data set name for the CSD would be:
DFHCSD DD DSN=CICSTS31.CICS.CICSHTH1.DFHCSD,DISP=SHR
If the data set is shared between an active CICS region and an alternate CICS region, use the generic APPLID, but if the data set is unique to either the active or the alternate CICS region, use the specific APPLID. For information about actively and passively shared data sets, see Setting up data sets for XRF.
Data set | DDNAME | Block or CI size (bytes) | Record format | Data set organization | Other comments |
---|---|---|---|---|---|
Auxiliary trace (See Setting up and using auxiliary trace data sets) | DFHAUXT DFHBUXT | 4096 | F | Sequential | 3 See MVS system data sets used by CICS for information about GTF. |
BTS local request queue. (See the CICS Business Transaction Services manual) | DFHLRQ | 1024 and 2560 | VB | VSAM KSDS | Required even if you do not use BTS facilities. BTS is described in the CICS Business Transaction Services manual. |
CAVM control (See Defining the CICS availability manager data sets) | DFHXRCTL | 4096 minimum | 1 | VSAM ESDS | Required if running CICS with XRF. |
CAVM message (See Defining the CICS availability manager data sets) | DFHXRMSG | 4096 minimum | 1 | VSAM ESDS | Required if running CICS with XRF. |
Catalogs (See Setting up and using catalog data sets) | DFHGCD
DFHLCD |
8192 & 2048 | VB | VSAM KSDS | Both data sets must be initialized before use. 2 |
CDBM group command (See Defining the CDBM GROUP command data set) | DFHDBFK | 8192 | VB | VSAM KSDS | Required only if you intend to use this function. |
CSD (See Setting up the CICS system definition data set) | DFHCSD | 8192 | VB | VSAM KSDS | -- |
DJAR mapping file (See Defining the EJB data sets) | DFHADJM | 8192 | F | VSAM KSDS | Required for CICS EJB development deployment tool only. This data set must not be shared. |
Dump (See Defining dump data sets) | DFHDMPA DFHDMPB | 32 760 (tape) or 1 track (DASD) | V | Sequential | For CICS transaction dumps only; see topic MVS system data sets used by CICS for information about system dumps. |
EJB directory (See Defining the EJB data sets) | DFHEJDIR | 1024 | F | VSAM KSDS | Required only for use by the regions (listeners and AORs) in a logical EJB server. This data set must be shared by all the regions in the EJB server. |
EJB object store (See Defining the EJB data sets) | DFHEJOS | 8192 | F | VSAM KSDS | Required only for use by the regions (listeners and AORs) in a logical EJB server. This data set must be shared by all the regions in the EJB server. |
Messages & codes (See Defining the CMAC messages data set) | DFHCMACD | -- | V | VSAM KSDS | Can be created and loaded by the DFHCMACI job. |
Temporary storage (See Setting up the temporary storage data set) | DFHTEMP | See Control interval size of temporary data set | 1 | VSAM ESDS | -- |
Transient data extrapartition (See Defining intrapartition data sets) 4 | From the DDNAME option in the resource definition | From the BLOCKSIZE option in the resource definition | From the RECORD FORMAT option in the resource definition | Sequential | The TYPE=SDSCI macro referred to has the same DSCNAME parameter as the TYPE=EXTRA macro |
Transient data intrapartition (See Defining extrapartition data sets) | DFHINTRA | See Space considerations of intrapartition data sets. | 1 | VSAM ESDS | -- |
Notes:
1 These data sets use control interval (CI) processing and therefore the record format is not relevant.
2 DFHGCD is the CICS global catalog data set, and in an XRF environment it is passively shared between the active and the alternate CICS regions. DFHLCD is the CICS local catalog data set, and this is a unique data set; each CICS region must have its own local catalog. See Setting up data sets for XRF for an explanation of actively and passively shared data sets in an XRF environment.
3 The CICS utility program, DFHTU640, prints and formats auxiliary trace data. For information about this CICS utility program, see the CICS Operations and Utilities Guide.
4 You do not have to specify all the data sets associated with extrapartition transient data queues in the CICS JCL this is because of the introduction of dynamic allocation of extrapartition transient data queue data sets. See the CICS Resource Definition Guide for more information.
You can define a temporary storage data set,or a transient data destination data set, as a single extent defined on a single volume. That data set must be big enough to hold all your data. Instead of defining one data set, which to cater for exceptional cases might have to be much larger than your average, you can define:
When you define more than one extent, CICS uses the extra extents only when the primary extent is full. You could make your primary extent large enough to meet average demand, and then have smaller secondary extents for overflow. In this way, you save space until it is needed. When each extra extent becomes full, VSAM creates another. VSAM continues to create extra extents, as needed, up to a maximum of 123 extents. The use of multiple volumes has no effect on this limit.
To allocate additional extents in the same volume, code a secondary extent operand on the RECORDS parameter:
RECORDS(primary,secondary)
To use single extents on multiple volumes, code:
RECORDS(primary) -
VOLUMES(volume1,volume2,volume3,.....)
For multiple extents on multiple volumes, combine both primary and secondary RECORDS operands with multiple VOLUMES operands:
RECORDS(primary,secondary) -
VOLUMES(volume1,volume2,volume3,.....)
If a particular volume causes performance bottlenecks, try single extents on multiple volumes.
Multiple extents over multiple volumes should be used if there is a probability that a volume will exhaust its free space before VSAM reaches its limit on extra extents. If this occurs, VSAM continues to create extra extents on the next volume in the list.
When specifying the number of buffers for temporary storage and transient data, you should consider the following possible performance impact:
Where names are allowed to be up to eight characters long, as for CICS APPLIDs, the general recommendation is that the letters CICS are used for the first four characters, particularly for production regions.