Tech Tip from Karina Pulinx, Principal Support Engineer for November 22, 2016.
This is another in the series of tips for CA Datacom Core Products Version 15.1 enhancement PTF RO92259.
RO92259 delivers 10 new features.
DBMUFPR ACCESS has been enhanced to allow for a new type of DF_DS_OP which can be used to defer the DATA Set of a URT OPEN.
The DF_DS_OP value allows reduced 24-bit memory in the MUF region when data sets are opened but not used to add or read data. If set for a base, the open of the base in support of a User Requirements Table (URT) performs the Directory CXX open processing and control handling. However, it does not open the data areas or validate them.
The data set open and validation occurs on the first command to add a row or read a row. Therefore, if there is no actual access of the data in the data set then it is not opened.
If all areas are accessed for data, then there is no actual savings of 24-bit memory. This applies to data areas, but not any index area.
Because of the design of the option, it might be valuable if you recycle a MUF which can cause hundreds or thousands of data areas to be opened. Without the option, the applications wait for all the areas in the opening URTs to be data set opened and validated. This takes a little time but is faster than the alternative. With the option in place, the opens complete faster and the application can get started on what it requires immediately. The actual data set open is deferred and only slows the initial read for a table in that area.
This option is active for user application URT opens in batch and CICS. It is ignored for DBUTLTY driven opens and also bases opened in support of MUF processing not user applications.
Datacom System databases and Virtual databases cannot be used with this option.
The option is expected to be done during the MUF enable. The ACCESS statement in MUF SYSIN supports a single base or a ranges of bases. Both can be stacked on the statement.
You can add the option later using a console-like command ACCESS DF_DS_OP with a single base. You can also remove the option using the console-like command ACCESS DF_DS_CL with a single base.