Controlling log data set characteristics
You might need to tune and modify log data set characteristics
after monitoring or after changing your requirements for system availability,
integrity, or operator handling. You can change characteristics for
the OLDS, WADS, and RECON data sets through the IMS commands.
Changing online log data set characteristics
Because you can restart IMS (warm start or emergency restart) with all input on SLDS, you can reallocate the OLDSs between a shutdown (or failure) and a subsequent restart. To restart IMS using SLDSs as input, you must delete the PRIOLDS and SECOLDS records from the RECON data sets.
Changing write-ahead data set characteristics
The write-ahead data set (WADS) contains log records that reflect completed operations and are not yet written to an online log data set. You can change the write-ahead data set (WADS) mode, add or remove a WADS, or change the space, location, or allocation of the WADS.
Changing system log data set characteristics
Converting from single to dual SLDSs requires modification in the skeletal JCL (ARCHJCL member) and in all your operational procedures using SLDSs. In the operational procedures, consider using the secondary SLDS when you experience errors in the primary one. No modification is required for online processing because IMS dynamically allocates SLDSs.
Changing RECON data set characteristics
You can change many aspects of the RECON data set by adding or removing spares, replacing the active data set, or changing it from single to dual mode.