MVS system data sets used by CICS

Besides its own system data sets, summarized in Table 3, CICS® also uses some MVS™ data sets. These are:

Table 7. MVS data sets used by CICS
Data set Owned or used by Other comments
SDUMP data sets MVS SDUMP macro Used by CICS for system dumps through the MVS SDUMP macro.
SMF data sets System management facility Used by CICS monitoring and statistics domains for monitoring and statistics records.
GTF data sets Generalized trace facility Used by CICS trace domain for CICS trace entries.

Recalculate the size of these system data sets, taking into account the increased volumes of data that CICS generates. For example, for an SDUMP data set you need at least 25 cylinders of a 3380 device, or the equivalent. For guidance information about calculating the size of SDUMP data sets, see the OS/390 MVS Initialization and Tuning Guide manual.

The SDUMP data sets can become full of unwanted SDUMPs that precede ASRA, ASRB, and ASRD abends (after message DFHAP0001). To prevent this, suppress such SDUMPs as described in topic Suppressing system dumps that precede ASRx abends.

If you are collecting CICS interval statistics frequently, or the volume of statistics at each interval is high, then you must take this into account when sizing your SMF data sets. Similarly, you must consider the amount of CICS monitoring data that is being written when CICS monitoring classes are active.

CICS can write records to SMF of up to 32756 bytes, resulting in SMF writing spanned records to the SMF data sets. For more efficient use of DASD, you should consider creating the SMF data sets to be used by CICS with a control interval size of either 16384 bytes (16KB) or 8192 bytes (8KB). If you use other control interval sizes you must consider the trade-off between efficient use of DASD, SMF data set I/O performance and the possibility of data being lost due to insufficient SMF buffers.

If you are running CICS with GTF trace on, make allowance for CICS trace entries in the GTF data sets.

For background information about SMF, and about other SMF data set considerations, see the OS/390 MVS System Management Facilities (SMF).

For programming information about CICS monitoring records and their sizes, see the CICS Customization Guide For programming information about CICS statistics records and their sizes, see the CICS Performance Guide. For background information about GTF, see the OS/390 MVS Diagnosis: Tools and Service Aids manual.

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