What are the standard system libraries?

z/OS® has many standard system libraries; here are a few that you will come across often.

z/OS standard system libraries include:

SYS1.PROCLIB: This library contains JCL procedures distributed with z/OS. In practice, there are many other JCL procedure libraries (supplied with various program products) concatenated with it.
SYS1.PARMLIB: This library contains control parameters for z/OS and for some program products. In practice, there may be other libraries concatenated with it.
SYS1.LINKLIB: This library contains many of the basic execution modules of the system. In practice, it is one of a large number of execution libraries that are concatenated.
SYS1.LPALIB: This library contains system execution modules that are loaded into the link pack area when the system is initialized. There may be several other libraries concatenated with it. Programs stored here are available to other address spaces.
SYS1.NUCLEUS: This library contains the basic supervisor ("kernel") modules of z/OS.
SYS1.SVCLIB: This library contains operating system routines known as supervisor calls (SVCs).

These libraries are in standard PDS format and are found on the system disk volumes.