A subsystem description defines how, where, and how much work enters a subsystem, and which resources the subsystem uses to perform the work. The following describes how the prestart job entries in the QUSRWRK (or QSYSWRK prior to OS/400® V5R2) subsystem description affect the DDM server.
A prestart job is a batch job that starts running before an application requester (AR) initiates communications with the server. Prestart jobs use prestart job entries in the subsystem description to determine which program, class, and storage pool to use when the jobs are started. Within a prestart job entry, you must specify attributes that the subsystem uses to create and manage a pool of prestart jobs.
Prestart jobs provide increased performance when initiating a connection to a server. Prestart job entries are defined within a subsystem. Prestart jobs become active when that subsystem is started, or they can be controlled with the Start Prestart Jobs (STRPJ) and End Prestart Jobs (ENDPJ) commands.