Modifying VLF

VLF can be modified using the MODIFY VLF,REPLACE,NN=xx command, instead of being stopped and restarted, so that its existing cache of objects can be retained. Use the command to start VLF with up to 16 concatenated COFVLFxx members of the logical parmlib, instead of the current members. The COFVLFxx parmlib members must contain valid CLASS statements.

The MODIFY VLF,REPLACE,NN=xx command can be used for the following actions:
  • Deleting existing classes
  • Adding new classes and their associated parameters
  • Deleting EDSN or EMAJ major names from existing classes
  • Adding EDSN or EMAJ major names to existing classes
  • Increasing MaxVirt for existing classes
  • Decreasing MaxVirt for existing classes
  • Changing AlertAge for existing classes.

For further information about using the COFVLFxx member, refer to z/OS MVS Initialization and Tuning Reference.

For details on using the MODIFY VLF,REPLACE,NN=xx command, refer to z/OS MVS System Commands.

Parent topic: Using the VLF macros