Generation Data Group (GDG)

September 18, 2010 Rui Miguel Feio

GDG is a collection of historically related non-VSAM data sets that are arranged in chronological order. Each data set within a GDG is called a generation data set (GDS) or generation. Within a GDG, the generations can have like or unlike DCB attributes and data set organizations. If the attributes […]

JCL most common operands

September 9, 2010 Rui Miguel Feio

1. JOB Statement REGION= Requests specific memory resources to be allocated to the Job NOTIFY= User to be notified at job completion USER= Userid to assume authority to the Job TIME= Limits the amount of time a program can run TYPRUN= Delays or holds the Job from running CLASS= Directs […]

Virtual Storage Access Method (VSAM)

September 9, 2010 Rui Miguel Feio

VSAM applies to both a data set type and the access method used to manage various user data types. VSAM data sets are held on direct access storage devices (DASD) auxiliary storage. VSAM divides its data set storage into control areas (CA), which are further divided into control intervals (CI). […]


September 8, 2010 Rui Miguel Feio

Linklist is used to improve the performance of program management and mechanisms utilized to locate and fetch Load modules, such as LLA and VLF. Linklist is a group of system and a user-defined Load library that is a continuation of SYS1.LINKLIB and also indicates the search order the system uses […]

Virtual Lookaside Facility (VLF)

September 4, 2010 Rui Miguel Feio

VLF keeps objects (for example Load modules) in Virtual Storage in order to save I/O operations that would load such objects. Designed primarily to improve performance by retrieving the most currently used objects from Virtual Storage rather then performing repetitive I/O operations from DASD. VLF can be configured by using […]

1 2 3 4