In my experience, academic theses are defended in public with permission — and perhaps protection — of high university officials, and this is often indicated on the title page.
Consider for example this dissertation (which contains a poem that I asked about).
The title page says:
D. F. G.
Consensu Ampliss[imae] Facult[atis] Philosoph[iae]
in Regia Academia Aboensi,
Matheseos Prosessore Reg. et Ord.
PUBLICAE CENSURAE SUBJICIT
Andreas Johannes Lexell
Die XXX Junii Anni MDCCLIX
LOCO HORISQUE A. M. SOLITIS.
Typis LAURENT. LUDOV. GREFINGII.
The bolded part says that the thesis was defended with consent from the great faculty of philosophy.
The title pages you show do not have a similar phrase, so it is possible that the abbreviation JSJP might have a similar role.
Based on this, I might guess iussu senatus, iussu praesidentis/praesidis, "by the order of the senate and the president [of the university]".
However, I would be much more confident about this theory if I knew what JUDPPO meant in your examples and DFG in mine.
My suggestion is merely an educated guess, but I leave it for others to judge whether it was educated enough.