Download and apply all the PTFs available (according to your preferred method - CSM, SMP/E, etc) into your TARGET library.
In case you have customized members in your USER runtime library, make sure to carry the changes over from the TARGET library into the corresponding USER one, so the new PTFs are also reflected there.
In order to apply the maintenance (PTFs) into your USER runtime libraries, please do the following:
1) Backup your USER runtime library
2) After identifying the member involved, copy/replace it from TARGET library to the USER one.
3) Restart TPX instances.
Note 01: Remember to review and re-add any previous customizations to the USER runtime library.
Note 02: If a RUNTIME load library is used, copy/replace all the member from TARGET library to the RUNTIME one.
Note 03: If an EXIT has been updated, you need to REASSEMBLE it in order for the customizations to take effect.
Make sure you follow the steps above everytime you apply a new PTF, so your TARGET library and USER runtime libraries are in Sync.